Red Blood Cell Antibodies Research Articles

X-linked sideroblastic anaemia in a female fetus: a case report and a literature review

BackgroundX-linked sideroblastic anaemia (XLSA) is commonly due to mutations in the ALAS2 gene and predominantly affects hemizygous males. Heterozygous female carriers of the ALAS2 gene mutation are often asymptomatic or only mildly anaemic. XLSA is usually characterized by microcytic erythrocytes (reduced mean corpuscular volume (MCV)) and hypochromia, along with increased red cell distribution width. However, in females with XLSA the characteristic laboratory findings can be dimorphic and present with macrocytic (elevated MCV) in addition to microcytic red cells.Case presentationWe report a case of fetal anaemia, presenting in the early third trimester of pregnancy, in a female fetus. Ultrasound findings at 29 weeks were of cardiomegaly, prominent umbilical veins, a small rim of ascites, and mean cerebral artery peak systolic velocity (PSV) value above 1.5 Multiples of the Median (MoM). She underwent non-invasive prenatal testing that determined the rhesus genotype of the fetus to be rhesus B negative. No red blood cell antibodies were reported. Other investigations to determine the underlying cause of fetal anaemia included microarray comparative genomic hybridization, serology to exclude congenital infection and a peripheral blood film and fetal bilirubin to detect haemolysis. The maternal grandmother had a history of sideroblastic anaemia diagnosed at the age of 17 years. The mother had mild macrocytic anaemia with haemoglobin of 10.4 g/dl and MCV of 104 fl. The fetal anaemia was successfully treated with two in utero transfusions (IUTs), and delivery occurred via caesarean section at 37 weeks of gestation. The red cell gene sequencing in both the mother and fetus were heterozygous for an ALAS2 mutation causing in utero manifestations of XLSA. The haemoglobin on discharge to the local hospital at five days of age was 19.1 g/dl. Subsequently, the infant became anaemic, requiring regular 3–4 monthly blood transfusions and demonstrating overall normal development. Her anaemia was unresponsive to pyridoxine.ConclusionsThis is one of four cases reporting multiple female members presenting with discordant clinical features of XLSA from being entirely asymptomatic to hydropic in utero. Our report is novel in that there are no previous cases in the literature of anaemia in a female fetus heterozygous for ALAS2 mutation.

Perinatal risk factors associated with severity of haemolytic disease of the foetus and newborn due to Rhc maternal-foetal incompatibility: A retrospective cohort study.

Anti-c is the third red blood cell antibody responsible for haemolytic disease of the foetus and newborn (HDFN) requiring intrauterine transfusion. We aimed to identify risk factors associated with HDFN and severe HDFN due to Rhc maternal-foetal incompatibility. A retrospective cohort study was conducted in Paris and the surrounding area (France), between 2013 and 2015. We included mothers and their children managed by the National Reference Centre in Perinatal Hemobiology for alloimmunization and maternal-foetal incompatibility for the Rhc antigen (N= 121). We conducted bivariate analyses to assess a relationship between perinatal factors (e.g., titre and concentration of anti-c antibodies, direct antiglobulin test) and HDFN, its severity and duration. The incidence of HDFN was 30% (n= 36), including 11% of severe HDFN (n= 13). Seven percent (n= 9) of neonates received at least one transfusion during the first week and 21% (n= 26) after this period until 3 weeks of life. During pregnancy, a concentration ≥7.5IU/ml and a titre ≥4 and above were associated with HDFN and severe HDFN (p< 0.05). At birth, the high intensity of the quantitative direct antiglobulin test was associated with HDFN and severe HDFN (p< 0.05). A concentration ≥15 IU/ml is the best factor (area under curve [AUC]=0.78) in predicting HDFN, followed by a titre ≥8 (AUC=0.76). Anti-c alloimmunization causes neonatal anaemia, which is often belated. Paediatricians have to be aware of these risk factors and organize prolonged monitoring of neonates.

Clinical and Economic Impact of Red Blood Cell Antigen Alloimmunization on Patients with Hereditary Hemorrhagic Telangiectasia

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare autosomal dominant disorder characterized by the presence of arteriovenous malformations which lead to repeated bleeding episodes for which Red Blood Cell (RBC) transfusions may be required. Previous research has shown that this patient population presents with high rates of alloimmunization against RBC antigens (15.29%) (Zheng Transfusion. 2018;58(3):775-780). However, the impact of such complications on clinical and economic outcomes has not been assessed previously. The present study aims to quantify the impact of alloimmunization on clinical outcomes and healthcare costs among HHT patients in a hospital setting.A cross-sectional study of alloimmunized and non-alloimmunized patients using the Premier Hospital chargemaster dataset from January 2015 to June 2019 was performed. Alloimmunization was defined based on the presence of antiglobulin crossmatch and RBC antibody identification laboratory codes in patient medical records. In order to assess the accuracy of this method of identification, the alloimmunization rates among discharges for patients diagnosed with HHT and myelodysplastic syndrome (MDS) for 2018 were extrapolated to the whole country and compared to reports in the literature (Zheng Transfusion. 2018;58(3):775-780, Singhal Haematologica. 2017;102(12):2021-2029). Consistent results were shown, 16.8% vs 15.3% and 11.5% vs. 11% for the HHT and MDS discharges, respectively.Alloimmunized and non-alloimmunized groups were matched for sex, age, admission date, and visit type (outpatient vs. inpatient). Diagnosis of HHT was defined using ICD-10 code I78.0. Cost per discharge for outpatient and inpatient visits, hospital and intensive care unit (ICU) length of stays (LoS), and inpatient mortality were both cases and controls. Bivariate comparisons were performed assuming a two-tailed test of significance and α level of 0.05 and multivariable regression models adjusting for diagnosis-related groups (incidence ≥1%) were performed.A total of 783 alloimmunized HHT cases were matched to 6,744 non-alloimmunized controls. Mean (SD) age was 65.7 (10.9) years for the alloimmunized (cases) and 59.4 (16.3) for the non-alloimmunized (controls), and slightly more than half of the population included in both groups were females (53.0% and 54.0% for the alloimmunized and non-alloimmunized groups, respectively).Outpatient visits were more common than inpatient admissions in both groups (52.6% and 71.4% of cases and controls, respectively albeit inpatient admissions were less common in both control groups (47.4% vs. 28.6%). Most common diagnoses leading to inpatient admission in both groups were disorders of the circulatory system (16.1% and 8.0%, respectively), followed by blood disorders for the alloimmunized group (9.8%) and disorders of the digestive system for the non-alloimmunized group (3.6%).Alloimmunized HHT patients presented with 22% longer hospitalizations (6.1 vs 7.3 days; p=0.0001) and 54% longer ICU stays (4.7 vs 7.2 days; p=0.0146), as well as a 40% increased likelihood of being admitted to the ICU. Inpatient mortality was higher among the alloimmunized population although it did not reach statistical significance (Odds Ratio: 1.53 [0.79; 2.96]; p=0.2092). Overall 12 (3.23%) and 59 (3.1%) deaths were reported for the alloimmunized and non-alloimmunized patient population, respectively. Median costs per discharge were significantly higher both for inpatient ($1,461; p=0.0202) and outpatient ($377; p<0.0001) visits within the alloimmunized population (Table 1).Presence of alloantibodies was associated with significantly worse clinical outcomes, increased healthcare resource use and higher costs within HHT patients. The increased prevalence of alloimmunization within the HHT population is not yet fully understood, and this study was not designed to determine whether prophylactic antigen matching would prevent alloimmunization in the HHT population. Further studies assessing the use of preventive strategies such as prophylactic antigen matching to prevent alloimmunization and its clinical and economic consequences could help determine whether antigen negative RBC units should be preferentially distributed to HHT patients. [Display omitted] DisclosuresGehrie: Grifols SSNA: Consultancy, Honoraria. Viayna: Grifols S.A.: Current Employment. Blanchette: Grifols SSNA: Consultancy; Novo Nordisk Inc.: Current Employment. Meny: Grifols SSNA: Current Employment. Noumsi: Grifols SSNA: Current Employment. Huber: Grifols SSNA: Current Employment. Runken: Grifols SSNA: Current Employment.

Red Cell Alloimmunization Is Associated with Higher Treatment Costs and Poor Health Outcomes Among Hemoglobin S-Beta Thalassemia Patients

Hemoglobin S (HbS) beta thalassemias (thal) are types of sickle cell disease (SCD) that result from the inheritance of one HbS gene and one β thalassemia gene. Red Blood Cell (RBC) alloimmunization is believed to be a major complication of transfusion therapy for HbS-thal patients. Indeed, among SCD patients generally, alloimmunization not only complicates the procurement of blood, but can also lead to life threatening delayed hemolytic transfusion reactions, and can be associated with a host of negative health outcomes including a higher risk of death. It is generally accepted that some alloimmunization events can be prevented via donor-recipient antigen matching, although this strategy is associated with higher costs and utilization of scarce resources (i.e.. antigen negative RBC units). The present study aimed to assess the clinical and economic implications of alloimmunization in HbS-thal patients.The Premier Hospital chargemaster dataset was used to perform a cross-sectional study matching alloimmunized and non-alloimmunized patients based on sex, age, date of admission, and type of visit (outpatient vs. inpatient). All outpatient and inpatient discharges from Jan 2015 to Jun 2019 were included in the study. Because there is not a specific laboratory code to designate alloimmunization, presence of both “antiglobulin crossmatch” and “RBC antibody identification” codes in a record was used as a surrogate for alloimmunization. Accuracy of this approach was validated by comparing the frequency of these codes among the hereditary hemorrhagic telangiectasia (HHT) and myelodysplastic syndromes (MDS) populations within the Premier dataset to the reported rates of alloimmunization for these entities in the medical literature (Zheng Transfusion. 2018;58(3):775-780, Singhal Haematologica. 2017;102(12):2021-2029). This comparison predicted a 16.8% alloimmunization rate in the HHT population (similar to the 15.3% reported in the literature) and an 11.5% alloimmunization prevalence in the MDS population (similar to the 11% reported in the literature).HbS-thal patients were identified based on diagnostic coding (ICD-10 code D57.4). Demographic, clinical and billing characteristics were retrieved. Cost per outpatient and inpatient discharge, hospital and intensive care unit (ICU) length of stay (LoS) and inpatient mortality were assessed for both alloimmunized and non-alloimmunized HbS-thal patients. Bivariate comparisons were performed, assuming a two-tailed test of significance and an α level of 0.05. Multivariable regression models adjusting for diagnosis-related groups with ≥1% incidence were performed.This approach permitted a total of 999 discharges corresponding to alloimmunized HbS-thal patients (cases) to be matched to 550 HbS-thal controls. Mean (SD) age was 35.1 (18.8) and 30.1 (18.6) for cases and controls, respectively. The percentage of females was slightly higher within the alloimmunized group (63.66% vs. 57.45%), and higher rates of inpatient visits were observed for the alloimmunized population compared to controls (67.9% vs. 33.1%).The multivariate models showed that alloimmunized HbS-thal patients presented significantly worse economic and clinical outcomes compared to their non-alloimmunized controls through all variables assessed. Median cost per discharge was $5,313 (p<0.0001) higher for alloimmunized inpatients and $1,014 (p<0.0001) higher for alloimmunized outpatients, compared to non-alloimmunized controls. Alloimmunized HbS-thal patients also experienced a 63% increase in hospital LoS (4.5 vs 7.4 days;; p<0.0001) and nearly over a 2.5-fold increase in ICU LoS (4.2 vs 10.0 days; p=0.0257). Alloimmunization in this population was also associated with a 3-fold increased risk of admission to intensive care (p=0.0032), longer stays in the ICU (p-0.0257), and a 3-fold increase in inpatient death (p<0.0001) (Table 1).The present study reveals that alloimmunization is associated with significantly longer hospitalizations and ICU stays, higher risk of ICU admission, greater inpatient death, and higher healthcare costs among patients with ICD-10 diagnosis of HbS-thal. These data seem to support the incremental costs and resource allocation decisions required to provide prophylactic antigen matching to HbS-thal patients, in an effort to diminish the risk of alloimmunization. [Display omitted] DisclosuresGehrie: Grifols SSNA: Consultancy, Honoraria. Viayna: Grifols S.A.: Current Employment. Blanchette: Grifols SSNA: Consultancy; Novo Nordisk Inc.: Current Employment. Meny: Grifols SSNA: Current Employment. Noumsi: Grifols SSNA: Current Employment. Huber: Grifols SSNA: Current Employment. Runken: Grifols SSNA: Current Employment.

Longer Hospitalizations, Increased Inpatient Mortality and Costs Are Associated with Alloimmunization Among Patients with Myelodysplastic Syndromes

Red Blood Cell (RBC) transfusions remain an important part of the management of anemia caused by myelodysplastic syndromes (MDS). Almost 90% of patients diagnosed with MDS require at least one RBC transfusion and 30%-45% require chronic transfusions (Singhal Haematologica. 2017;102(12):2021-2029). Importantly, it is estimated that 11% of MDS patients form alloantibodies as a result of RBC transfusions. Despite this relatively high alloimmunization rate, MDS patients are almost never prophylactically transfused with RBCs from antigen-matched donors, a strategy which has been shown to reduce the incidence of alloimmunization among patients with sickle cell disease, but which also increases costs and utilizes a limited resource (antigen negative RBCs). Herein, we present the economic and clinical burden of RBC alloimmunization in MDS patients, in order to better inform decision making regarding prophylactic RBC antigen matching.A cross-sectional study using the Premier Hospital chargemaster dataset was performed. All outpatient and inpatient discharges from January 2015 to June 2019 were included. MDS was defined using ICD-10 code D.46. Because there is no diagnosis code for alloimmunization, alloimmunized patients were identified based on the presence of antiglobulin crossmatch (CXM) and RBC antibody identification (RAI) codes in Premier records. This approach was validated by comparing the published rate of alloimmunization observed in patients diagnosed with MDS as well as hereditary hemorrhagic telangiectasia (HHT; another population with a relatively high alloimmunization rate) to the prevalence of both CXM and RAI codes in the Premier dataset during 2018. The comparison showed that our approach successfully modeled the published alloimmunization rates in HHT (16.8% vs 15.3%) and MDS (11.5% vs 11%) (Zheng Transfusion. 2018;58(3):775-780, Singhal Haematologica. 2017;102(12):2021-2029).Demographic, clinical, and billing characteristics were gathered. Total cost per discharge, hospital and intensive care unit (ICU) length of stay, and inpatient mortality, were calculated for both study groups and compared. Bivariate comparisons were performed, assuming a two-tailed test of significance and an α level of 0.05. Multivariable regression models adjusting for sex, age, admission date, visit type (outpatient vs. inpatient) type of MDS based on the World Health Organization (WHO) classification and diagnosis-related groups (DRG) with an incidence ≥1% of inpatient visits were performed.Overall, 179,819 MDS patient encounters were identified. Of these, 11,948 were alloimmunized and 167,871 were not alloimmunized (Table 1). When assessing incremental economic and clinical outcomes for the alloimmunized MDS population, multivariate models showed that alloimmunization led to significantly worse economic and clinical outcomes through all variables assessed (Table 2). The incremental median cost per inpatient and outpatient visit for the alloimmunized population were $2,829 (p<0.0001) and $630 (p<0.0001) higher, respectively. Alloimmunized patients had significantly longer inpatient hospitalizations (7.2 vs 8.2 days; p<0.0001) as well as longer ICU stays (4.4 vs 6.8 days; p<0.0001). Alloimmunized)A patients also encountered a 38% increased risk of being admitted to intensive care, and a 30% higher risk of inpatient mortality.This analysis discloses that alloimmunization is associated with higher healthcare costs and worsened clinical outcomes in the MDS population. Further work is needed to clarify whether alloimmunization is causally related to these outcomes, or whether alloimmunization is incidentally more common among patients with worse disease. The present study was not designed to assess the effectiveness of prophylactic antigen matching in the prevention of alloimmunization in the transfused MDS population, and further work is needed to confirm the findings presented herein. However, decisions regarding provision of antigen-matched RBCs to MDS patients should consider the potential for downstream consequences of alloimmunization. [Display omitted] DisclosuresGehrie: Grifols SSNA: Consultancy, Honoraria. Viayna: Grifols S.A.: Current Employment. Blanchette: Grifols SSNA: Consultancy; Novo Nordisk Inc.: Current Employment. Meny: Grifols SSNA: Current Employment. Noumsi: Grifols SSNA: Current Employment. Huber: Grifols SSNA: Current Employment. Runken: Grifols SSNA: Current Employment.

High-sensitivity detection of clinically significant red blood cell antibodies by the column agglutination technique.

The detection of clinically significant antibodies to red blood cell antigens is important for the selection of compatible blood for patients. The conventional test tube technique (CTT) is commonly used as the gold standard test, but manual testing and visual detection of hemagglutination may produce errors. A more recently developed method, the column agglutination technique (CAT), facilitates ease of testing. To investigate the specificity and sensitivity of the CAT compared to the CTT for the screening of clinically significant antibodies from the Rh blood group. Standard antibodies to the Rh blood group, anti-D, -C and -E, were used as examples of clinically significant antibodies in transfusion science. The antibodies were serially diluted by two-fold, then reacted with screening cells with different antigen expression. The hemagglutination reaction was investigated using both techniques, and the grades and scores of the reactions were used to analyze the sensitivity and specificity of the CTT and CAT. The CAT had a better sensitivity than the CTT. The lowest antibody dilution of 1:8192 could be detected using CAT, while a dilution of only 1:2048 could be detected with CTT. However, the CTT and CAT were equal in specificity. The 2 techniques specifically detected all antibodies to the screening cells. Both the CAT and CTT showed 100% specificity. However, the CAT exhibited more sensitivity than the CTT, and can be used in substitution of, or in parallel with, the CTT technique for red blood cell phenotyping, antibody screening, identification, and crossmatching.

Management and clinical consequences of red blood cell antibodies in pregnancy: A population-based cohort study.

Anti-D alloimmunization is the most common cause of severe hemolytic disease of the fetus and newborn (HDFN). The management of pregnancies affected by less frequent red blood cell (RBC) antibodies poses a challenge to clinicians, and perinatal outcomes are less well described. This study aimed to describe the frequency of clinically significant RBC antibodies in our pregnant population and analyze the risk of prenatal and postnatal treatment for HDFN in relation to our national risk classification system and management guidelines. A retrospective cohort study in the population of all alloimmunized singleton pregnancies in the Stockholm region 1990-2016. Descriptive summaries of different RBC antibodies and pregnancy outcomes were presented, the risks of intrauterine blood transfusion (IUT) and neonatal treatment for HDFN were estimated by type of antibodies. Of the 1724 alloimmunized pregnancies, 1079 (63%) were at risk of HDFN and constituted our study cohort. Anti-D was detected in 492 (46%) pregnancies, followed by anti-E in 161 (15%), and anti-c in 128 (12%). Eighty-seven (8%) pregnancies had IUT, with the highest risk in pregnancies affected by anti-D combined with other antibodies. The maximum titer recorded before IUT was 64 or above, except for two pregnancies affected by anti-c, for which the maximum titers were 8 and 16. For the 942 (95%) live-born neonates from 992 alloimmunized pregnancies without IUT, the median gestational age at birth was 38+5 weeks compared with 35+5 weeks for those who had IUT. Neonatal treatment was most common in the anti-D alone and anti-D combined groups, with 136 (57%) and 21 (44%), respectively, treated with phototherapy and 35 (15%) and 9 (20%) receiving exchange transfusions, respectively. For pregnancies complicated by moderate- and low-risk antibodies, phototherapy was less frequent (32 [36%] and 21 [19%]) and exchange transfusion was rare (5 [6%] and 3 [3%]). Anti-D, especially in combination with other antibodies, presents the highest risk of severe HDFN. The classification of less frequent and less well-known RBC antibodies into risk groups can help clinicians in assessing the risk of HDFN and counseling alloimmunized pregnant women regarding the risk of prenatal and postnatal treatments.

Immunohematology and Transfusion Support of a Patient with Acute Myeloid Leukemia and an Anti-Vel

BackgroundTransfusion support of cancer patients presenting with red blood cell (RBC) antibodies against high-incidence antigens is a challenge for hospital-based Transfusion Services. For patients with antibodies against the high-frequency Vel antigen, only 0.0004% of blood donors will be Vel antigen-negative. Anti-Vel is notorious for looking like a benign, cold-reactive IgM antibody or a “high-titer, low-avidity” antibody; however, Vel-antibodies can fix complement at body temperatures and can cause severe hemolytic transfusion reactions. The immunohematology workup and RBC transfusion support are reported for a patient who developed an anti-Vel and other RBC antibodies during chronic transfusion therapy for myelodysplastic syndrome, with progression to acute myeloid leukemia. She was also evaluated for hematopoietic stem cell transplantation (HSCT).MethodsImmunohematologic workups were performed at a regional immunohematology reference laboratory. Since the patient had a positive autocontrol and a positive direct antiglobulin test (DAT), allogeneic adsorptions were performed at 37°C using R1R1, R2R2 and rr RBC reagents. Adsorbed plasma and eluates from adsorbed RBCs were then tested for alloantibody detection using manual tube method at both LISS and PEG reactivity. In preparation for possible HSCT, RBC alloantibody titers and monocyte monolayer assay (MMA) were performed. All samples were collected with pediatric phlebotomy tubes whenever possible.ResultsThe patient was a 66 year old woman with a myelodysplastic syndrome that transformed to acute myeloid leukemia (AML) with complex karyotype a year later. The RBC reference workup identified alloantibodies reacting to the high-incidence Vel antigen as well as low-incidence Yt(b) and Cw antigens. The patient's plasma was non-reactive with three of four Vel-negative (-) cells, whereas the reactive cell was Cw positive (+) and Yt(b+). Two allo-adsorptions were performed to remove anti-Vel. Upon repeat testing, anti-Cw was identified by LISS indirect antiglobulin test. Eluate from adsorbing RBCs was reactive with Vel- and Yt(b+) cells, suggesting presence of anti-Ytb. In preparation for HSCT, anti-Vel and anti-Cw were titered at 0 and 64, respectively. MMA for anti-Vel ranged at 0.2-2% (normal <3%). Nevertheless, the hospital-based Transfusion Service provided rare ABO/Rh Vel- CW- Yt(b-) crossmatch-compatible RBC to minimize the potential for stimulating anti-Vel, which might compromise a Vel+ HSCT. The patient required about 1 RBC unit per week to maintain hemoglobin above 4.5 g/dL. The Transfusion Service coordinated a search for antigen-negative RBCs with a national rare donor program, allowing at least 4 rare RBC units to be available at all times. Over an 18-month time period, the patient received 62 RBC Vel- units: 45 out of 62 (73%) were Cw- and 17 were Cw-unscreened but C-. Later in the patient's course, her transfusion rate increased to 2 RBC units per week. Because insufficient Vel- units were available within the USA, an international search by a rare donor program identified Vel- donors in Europe. FDA approval was obtained to import the rare units. She received 2 units from Spain and 2 units from Switzerland. Her leukemia progressed, and transfusion support was discontinued.ConclusionCoordination between hospital-based Transfusion Service, hematologists, and rare donor programs is required for rare RBC transfusion support in patients with antibodies against high-incidence antigens. A transfusion threshold of 4.5 g/dL may be tolerated when availability of rare RBC units is limited. DisclosuresNo relevant conflicts of interest to declare.

HLA and HNA Antibodies Are More Prevalent in Multiparous Women with Red Blood Cell Alloimmunization

Background: Leukocyte antibodies against HLA class I, class II and human neutrophil antigens (HNA) are formed from exposure to these antigens by transfusion, pregnancy or transplant, and may be associated with transfusion-related acute lung injury (TRALI) and immune neutropenias. Risk factors for acquisition of leukocyte antibodies are yet to be determined and present great importance for the prevention of severe and fatal transfusion reactions.Aims: To compare the prevalence of leukocyte antibodies in women with or without red blood cell (RBC) alloimmunization.Methods: This transversal study included women whose only stimulus to alloimmunization was pregnancy, with no transfusion history. We analyzed 147 blood samples from women with RBC alloimmunization, confirmed by the investigation and identification of RBC antibodies by the DG Gel-Card technique (Grifols-Spain). The control group consisted of 563 blood donors women with pregnancy history but without RBC alloimmunization. The identification of leukocyte antibodies was performed by: 1) granulocyte agglutination test (GAT), 2) white cell immunofluorescence test (Flow-WIFT), both tests using a panel of neutrophils obtained from three donors with previous HNA genotyping, and 3) bead-based assay - LABScreen Multi (LSM) (One Lambda), capable of detecting antibodies against HNA-1a, -1b, -1c, -2, -3a, -3b, -4a, -5a, -5b and HLA class I and II antigens. The identified HNA antibodies were confirmed by genotyping the corresponding antigen.Results: In the cohort of women with RBC alloimmunization we found 179 RBC antibodies: anti-D (30.7%), anti-Lea (21.3%), anti-C (15.1%), anti-E (8.9%), anti-K (5.6%), anti-M (5.6%) and other antibodies (12.8%). We identified 74/147 (50.3%) samples with anti-HLA antibodies and 11/147 (7.5%) samples with anti-HNA antibodies with the following specificities: 5/11 anti-HNA-1a, 2/11 anti-FCγRIIIb and 4/11 anti-HNA-3b. In the control group, we found 238/563 (42.3%) samples with anti-HLA and 24/563 (4.3%) samples with anti-HNA: 8/24 anti-HNA-1a, 01/24 anti-HNA-1c, 03/24 anti-HNA-2, 02/24 anti-HNA-3a, 5/24 anti-HNA-3b, 03/24 anti-HNA-5a and 02/24 anti-HNA-5b. Regarding the gestational history, 82/147 (55.8%) women in the group with RBC alloimmunization and 493/563 (87.6%) in control group had two or more pregnancies. The statistical analysis was performed in total samples, regardless the number of pregnancies, however no significant difference was observed in the prevalence rate of anti-HNA and anti-HLA between the two groups (p=0.10 and p=0.07, respectively). When the analysis was stratified including only multiparous women (two or more pregnancies) the prevalence of HNA alloimmunization was statistically significant in the group of women with RBC alloimmunization: 9/82 (11%) versus 23/493 (4.7%) blood donors, p=0.02, OR=2.52 (95% CI=1.15-3.79). Similarly a higher prevalence of HLA antibodies in the group of multiparous women with RBC alloimmunization was also observed: 51/82 (62.2%) versus 224/493 (45.4%), p=0.004, OR=1.97 (95% CI=1.18-2.71).Conclusions: The data show that RBC alloimmunization was significantly associated with the development of antibodies against leukocytes (anti-HNA and anti-HLA). A higher frequency of HNA alloimmunization (11%) observed in the group of multiparous women with RBC alloimmunization compared to the control group (4.7%), suggest that they are better immune responders and that they react strongly to allogeneic exposure. DisclosuresNo relevant conflicts of interest to declare.

Epidemiologic Characterization of Transfusion Recipients with Red Blood Cell Alloantibodies from Four US Regions: Evidence from the REDS-III Recipient Database

Introduction: Red blood cell (RBC) alloimmunization is one of the most common complications of RBC transfusion. Despite the fact that alloimmunization impacts many transfusion recipients, the lack of standardized alloimmunization registries in the US has prevented large studies from being completed. Through the development of a uniform electronic research database, we investigated alloimmunization rates and diagnoses in inpatients and outpatients across the US.Methods: The REDS-III recipient database, established in 2013, houses demographic, diagnostic, transfusion, laboratory, and other information on inpatients and outpatients at 12 hospitals in 4 geographic regions. For this study, an antibody “responder” (R) was defined as an individual who had a putative transfusion (or pregnancy)-associated red cell antibody identified by screen at any point during the study period, independent of documented RBC exposure or pregnancy during the study period. An antibody “non-responder” (NR) was defined as an individual who was transfused with at least one unit of RBCs during the study period, and had a negative antibody screen at least 15 days post-transfusion. Anti-D antibodies were excluded from studied females, given an inability to distinguish passively administered anti-D in the database from authentic alloantibodies. Demographics, blood type, ICD9/10 codes, and antibody screen results were compared for R and NRs. Odds ratios were calculated for the likelihood of being a R or NR, based on the presence or absence of select chronic disease states.Results: 612,417 patients were recorded in the REDS recipient database from 2013-2016. 318,918 unique patients in the database had an RBC antibody screen during the study period. Of these, 6597 had at least one transfusion-associated RBC alloantibody identified by routine antibody screen (overall alloimmunization rate among all screened patients independent of RBC exposure = 2.07%). 63.8% of the R were female (alloimmunization rate 2.97%) and 36.2% were male (alloimmunization rate 1.35%). 30,468 unique patients (49.8% female and 50.2% male) were NR; the mean RBC exposure during the study period was similar between R and NR (mean, s.d., and median of 8.8, 18.2, and 4 units versus 9.3, 14.3, and 5 units). Approximately 60-70% of the antibodies in R were pre-existing, and the remainder were generated during the study period. Few children under 10 years of age were R compared to older age groups; an equation of R/R+NR = 26/26 + 467 = 5.3%. There were no differences in R vs NR by A/B/O blood type, though Rh negative patients (R/R+NR of 1175/1175 + 3901 = 23.1%) were significantly more likely to be R than Rh positive patients (R/R + NR of 5365/5365 + 26544 = 16.8%). .A total of 8892 clinically significant antibodies were detected, including 4749 (53.4%) in the Rh family (2588 anti-E, 780 anti-C, 556 anti-c, 105 anti-e, 525 anti-D), 1937 (21.8%) in the K family, 912 (10.3%) in the Kidd family, and 669 (7.5%) in the Duffy family, among others. Patients with sickle cell disease (n=554, OR 2.6, p<0.0001), sickle cell trait (n=117, OR 1.8, p=0.02), 'coronary atherosclerosis or heart disease (n=12,403, OR 1.2, p<0.0001), lupus (n=969, OR 1.3, p=0.002), rheumatoid arthritis (n=1213, OR 1.2, p=0.01), and myelodysplastic syndrome (n=1162, OR 1.3, p=0.0008) were more likely to be R than NR. In contrast, patients with leukemia (n=2801, OR 0.5, p<0.0001), solid tumors (n=17,513, OR 0.6, p<0.0001), and solid organ transplant (n=1491, OR 0.7, p=0.0001) were less likely to be R than NR.Conclusions: Data collected in this multi-center recipient database provide the largest RBC alloimmunized patient cohort ever studied in the US. The 2.07% overall rate of alloimmunization is similar to that reported in other retrospective studies, with females having higher alloimmunization rates than males. Rh negative individuals were significantly more likely to be alloimmunized than Rh positive patients, despite the exclusion of anti-D antibodies in females. Other unexpected findings include the predisposition to alloimmunization observed in patients with sickle cell trait and coronary artery disease. Ongoing studies are investigating the timing of RBC exposure to new antibody formation in this patient cohort, as well as potential physiologic explanations for the chronic disease associated findings. DisclosuresNo relevant conflicts of interest to declare.

A case series highlighting a common approach to identifying anti-Jk3.

Abstract The Kidd-null phenotype, Jk(a–b–), is rare, and a patient with this phenotype may develop anti-Jk3, a red blood cell (RBC) antibody reactive with a domain common to both Jka and Jkb. Like other antibodies to high-prevalence antigens, the presence of this antibody poses challenges in the immunohematologic evaluation of these patients. Thoughtful laboratory testing is necessary to resolve the antibody specificity and to reveal other underlying antibodies. Moreover, the rarity of the Kidd-null phenotype makes finding blood donors difficult for those who need transfusion and have developed anti-Jk3. This review describes methods used in identifying anti-Jk3 in four pregnant patients. Blood bank records were retrospectively reviewed to illustrate the common approach in anti-Jk3 identification. In all cases, pertinent blood bank history was gathered, and extended RBC phenotyping was performed, followed by adsorption studies and testing of selected RBCs. Underlying antibodies were found in two of the cases. This review also reiterates some common challenges encountered with Kidd antibody analysis and highlights the importance of patient ethnic ancestry and obtaining accurate patient transfusion history.

Rates of delayed hemolytic transfusion reactions observed in a trauma center.

Delayed hemolytic transfusion reactions (DHTRs) are reported to be rare occurrences but may be more frequently observed in the trauma setting where patients are heavily transfused, followed over long inpatient admissions, and have frequent subsequent blood counts as they undergo multiple surgical interventions. We examined the rates of DHTRs on a per transfusion and per patient basis in an academic county hospital with a level 1 trauma center serving a four-state region and over a 3-year period. DHTRs were entered sequentially into a registry as they were observed, and a retrospective review of all new alloantibodies detected was performed to identify any additional DHTRs. The number of units of red blood cells (RBCs), the number of unique patients, types of alloantibodies, and number of transfusions were extracted from blood bank records. Twenty-nine DHTRs were observed from January 1, 2017, through December 31, 2019, from newly observed alloantibodies after a median of 12 red blood cells (RBCs) transfusions per patient. These reactions occurred in response to 24,633 unique transfusions in 6905 unique patients, so the observed rates were about 1:849 RBC transfusions and 1:238 transfused patients. Evidence of delayed hemolysis was seen in five additional patients who were transfused during emergency resuscitation and later found to have had known RBC antibodies. We report a higher rate of DHTRs than previously described to demonstrate that DHTRs are not rare in trauma centers.

Effect of fennel essential oil on performance, serum biochemistry, immunity, ileum morphology and microbial population, and meat quality of broiler chickens fed corn or wheat-based diet

ABSTRACT 1. The effect of Foeniculi aetheroleum essential oil (EO) on growth performance, nutrient utilisation, serum biochemistry, immune response, ileum morphology, microbial population and meat quality of broiler chickens fed a corn- or wheat-based diet were determined. 2. A total of 360 broiler chickens were arranged in a 2 × 2 factorial assay in a completely randomised design with six replicates and 15 birds per experimental unit. Birds were fed corn- or wheat-based diets supplemented with (200 mg/kg) or without fennel EO. 3. Birds fed wheat-based diets had lower BWG and FCR during grower period and lower FI during finisher period as compared to those fed corn-based diet (P < 0.05) whereas addition of fennel EO decreased chickens BWG during finisher period and EPEF, both in wheat or in corn-based diets. Dietary treatments had no effect on serum glucose, triglyceride, cholesterol, LDL-cholesterol, AST, ALT, ALP, and MDA concentrations (P < 0.05). 4. Antibody titres against avian influenza and sheep red blood cell antibody titres, crude protein and crude fat utilisation, villus height, crypt depth and epithelium thickness were not influenced by dietary treatments (P > 0.05). Inclusion of Fennel EO to the corn-based diet resulted in greater villus width and villus surface area while it reduced lamina propria thickness (P < 0.05). Fennel EO reduced ileal E. coli and Lactobacillus spp. populations (P < 0.05). Dietary treatments had no significant effect on meat pH, cooking loss, drip loss, crude protein, crude fat content and cholesterol concentration of breast and thigh meat, total phenolic and MDA concentrations, and breast meat sensory parameters (P > 0.05). 5. These results showed that addition of fennel EO to wheat-based diets had a negative effect on chicken growth performance variables and decreased gut E. coli populations. However, immunity, meat quality and nutrient utilisation were not affected by dietary treatments.

Red blood cell alloimmunization in pregnancy: A 10-year single-center study

Background/Aim. Pregnancy-induced red blood cell (RBC) alloimmunization is important not only because of the possible negative effects on subsequent pregnancy outcomes in case the fetus carries the antigen but also because of the optimal trans-fusion management in cases of obstetric hemorrhage. Timely detection of RBC antibodies is part of testing, prevention, and treatment strategy, aimed at achieving better outcomes for alloimmunized mothers with an affected fetus. The aim of the study was to determine the frequency and specificity of alloantibodies among pregnant women from the South Backa District, Serbia, with special attention to the incidence of anti-D alloantibodies. Methods. A retrospective study was conducted in the Blood Transfusion Institute of Vojvodina and covered the period from January 1, 2010, to December 31, 2019. Screening and antibody identification were performed by an indirect antiglobulin test in gel-microcards (ID-Card Liss/Coombs) with two test RBC (ID-DiaCell I-II screening cells, Bio-Rad, Cressier, Switzerland) on an automated system (IH-500, Bio-Rad). Results. Among 25,694 tested pregnant women, 1.38% were actively immunized, while 1.12% of women acquired antibodies in the current pregnancy. Among 3,622 (14.09%) RhD-negative women, 1.77% produced anti-D antibodies during the ongoing pregnancy. Distribution of anti-body specificity was: anti-D 23.34%, anti-M 11.85%, anti-E 9.41%, anti-K 9.41%, anti-C 5.92%, anti-Fyb 5.92%, anti-c 3.13%, anti-S 3.13%, anti-Lea 3.13%, anti-Leb 3.13%, anti-Cw 1.75%, anti-Jka 1.40%, anti-P 1.05%, anti-Lub 0.70%, anti-Fya 0.35%, autoantibody of undetermined specificity 0.70%, and irregular antibodies of undetermined specificity 15.68%. Conclusion. Immunoglobulin prophylaxis has led to a significant reduction in the frequency of D-alloimmunization among pregnant women in the South Backa District over the last ten years. However, the incidence of anti-D antibodies is still significantly higher than in published data for developed countries. We also identified the other, less commonly present, clinically significant antibodies. There is a need to introduce uniform recommendations for immunohematological testing in pregnancy on the territory of the Republic of Serbia in accordance with modern requirements.

Stimulation of humoral and cell-mediated immunities in healthy and cyclophosphamide-induced immunosuppressed rats by the lyophilized Houttuynia cordata fermented drink

ABSTRACTHouttuynia cordata fermented drinks (HCFDs) are dietary liquid supplements widely marketed and consumed for immune enhancement. In this study, the acute oral toxicity and immunostimulatory activity of the selected lyophilized HCFD in healthy and cyclophosphamide-induced immunosuppressed rats were evaluated. The lyophilized selected commercialized HCFD was safe in animal model as there was no acute oral toxic death at up to 2000 mg/kg in male Wistar rats. After 14 days of treatment, in immunosuppressed rats, lyophilized HCFD enhanced rat body weight gain and significantly increased spleen index at a dose of 100 mg/kg. Moreover, B-cell proliferation and anti-sheep red blood cell antibody production were significantly increased at doses of 100 and 200 mg/kg, respectively. The delayed-type hypersensitivity response was significantly stimulated at a dose of 200 mg/kg. These findings exhibited the immunostimulatory activity of the lyophilized HCFD by enhancing the immune responses in both humoral and cell-mediated immunities in immunosuppressed rats.

A case of hyperhaemolysis syndrome in a pregnant Chinese woman with β‐thalassemia during perinatal transfusion

To report a case of hyperhaemolysis syndrome (HHS) that occurred during perinatal blood transfusion in a pregnant Chinese woman with β-thalassemia to deepen the understanding of HHS and the risk of transfusion therapy for patients with thalassemia. Most HHS cases occur in people with sickle cell disease. So far, no cases of HHS have been reported in the Chinese population. Here, we report a pregnant Chinese women with β-thalassemia experiencing HHS. The patient received ABO- and RhD-matched red blood cell transfusion from six blood donors in four perinatal transfusions. Haemoglobinuria and lower haemoglobin levels compared to those before transfusion were observed after each transfusion, and the lactate dehydrogenase was consistently elevated. The blood samples were collected at different time points during the hospitalisation for direct antiglobulin test (DAT), antibody screening test and acid elution test. The antigens of six blood donors were identified, and the cross-matching tests were repeated using the blood sample of the patient with specific irregular antibodies after the last transfusion. The DAT of the patient was negative for anti-IgG and positive (1+) for anti-C3d, and no red blood cell antibodies were detected in the eluent before, between and after transfusions. Before and between transfusions, blood samples were negative for red blood cell irregular antibodies, whereas IgM anti-P1 and IgG anti-Jka were detected in blood samples the next day after the last transfusion. In the six donors, two were negative for P1 and Jka , one was positive for P1 and negative for Jka , and three were negative for P1 and positive for Jka . The tentative cross-matching tests using the indirect antiglobulin method in saline showed that only agglutination occurred in the blood samples of the patient collected after last transfusion and the three Jka -positive blood donors. The clinical manifestations and laboratory test results suggested that HHS occurred in this patient with β-thalassemia after each transfusion. Clinicians should be aware that HHS can occur with compatible blood transfusion.

Outcomes of Chronic Automated RBC Exchange Program in Omaha, Nebraska 2015-2020

Background: Red blood cell exchange (RBCX) is an effective therapy in the treatment of different hemoglobinopathies. The University of Nebraska Medical Center (UNMC) established a chronic RBCX program in November 2015, which took care of patients with multiple hemoglobinopathies. In this study, we aim to evaluate the outcomes of this program. Methods: This is a retrospective study. After an IRB approval, we reviewed the charts of patients who were enrolled in the chronic RBCX program between 11/2015-7/2020 at UNMC. Data was collected to evaluate indications of RBCX, types of hemoglobinopathies, hemoglobinopathies' complications before and after the enrollment in the program, and assessment of hospital visits before and after enrollment in the program. Results: In November 2015, the chronic RBCX program was established in Nebraska. Since the start, 24 patients came through the program and 20 patients are still actively enrolled and undergoing regular exchange transfusions. The four patients who left the program did it for the following reasons: moving out of state, stem cell transplant and change to different treatment modality. Four of 24 patients were beta thalassemia patients (two of them with combined HbE/beta thalassemia). Twenty patients had sickle cell disease with two of them having combined beta thalassemia and HbS and one with alpha thalassemia and HbS. The indications ranged from history of stroke, intracranial vascular stenosis, acute chest syndrome (ACS), iron overload, multiple vascular occlusive crises (VOC) and intolerance of medications with most of the patients having multiple indications from the list above (Figure 1). There are several positive outcomes from being on the program. In the patients who had been on the program for at least one year (n=11), nine started the program with iron overload and all of them had a significant decrease in serum ferritin (average 751 ng/mL) with three patients returning to normal range. In the patients who had been in the program at least six months (n=16), 13 patients started with iron overload with five returning to normal range and average decrease in ferritin of 585 ng/mL. Another positive outcome is the number of emergency department (ED) visits for pain crisis. We noted reduction in ED visits in all patients who were in the program for at least six months (n=14), with the exception of one patient where the visits were likely the part of drug seeking behavior. In fact 12 of 13 patients had one or no ED visits within one year after starting on the chronic exchange program having had from 2-11 visits a year prior. None of the patients in the program experienced more severe complications of sickle cell disease, like stroke and acute chest syndrome, while on the program. Due to high volumes of transfusion, there is a big concern about developing red blood cell antibodies in sickle cell disease patients who in general have higher red blood cell antibody burden. Out of 24 patients in the program, six had pre-existing antibodies. For the duration of the program, no new alloantibodies were discovered in the chronically exchanged patients despite high transfusion volumes (range 14L-30L/year). The transfused blood was matched for Rh and Kell antigens for the patients with no antibody history. The patients with previous antibody history had additional matching for the antigen to which antibody was directed. Conclusion:Automated chronic RBCX transfusion program is safe to perform. It leads to significant reduction in volume overload and ED visits. Performing high volume transfusions outside of acute sickle cell crisis and with Rh and Kell matched units prevents formation of RBC antibodies Disclosures Gundabolu: BioMarin:Consultancy;Bristol Myers Squibb pharmaceuticals:Consultancy.

Immune Hemolysis after a Hematopoietic Progenitor Cell Transplantation for Sickle Cell Disease: A Case Report

Background:The incidence of Delayed Hemolytic Transfusion Reaction (DHTR) is 0.04% but is higher in patients with sickle cell disease (SCD). Although it has been reported in hematopoietic progenitor cell (HPC) transplantation, its incidence in SCD following nonmyeloablative HPC transplantation remains unknown. We report a recipient with blood group O who received a nonmyeloablative HPC transplantation with blood group A three years ago. She is now typing as blood group A and developed a DHTR after receiving group A red blood cells (RBC). Case Report:A 42-year-old female was transferred from an outside hospital (OSH) for management of Acute T-Cell Lymphoblastic Leukemia. Three years prior, she received a group A+ matched sibling nonmyeloablative HPC transplantation for SCD. Her original blood group was O+, and she had a history of clinically significant RBC alloantibodies (anti-E, anti-C, anti-Goa, anti-Kell, and anti-Jkb). On admission to OSH (Day 1), the type and screen showed group A+ without ABO discrepancy. The antibody screen was negative. The OSH blood bank was unaware of her immunohematologic history, because it was not communicated to them by the OSH hematologists, and the only documented diagnosis was that of acute leukemia. Per SOP, OSH performed only immediate spin crossmatch. She was transfused three units of A+ RBC at OSH in preparation for her transfer to us on Day 3 (Fig. 1). At admission to our hospital, her laboratory parameters were suggestive of both tumor lysis syndrome and hemolysis. Her type and screen specimen was grossly hemolyzed. She typed as Group A+. The Direct Antiglobulin Test (DAT) was positive with polyspecific antisera, positive for IgG and negative for bound complement factors. Antibody screen was negative except for the anti-Goa. In the eluate, we identified anti-A or anti-A,B, which were not differentiated for lack of clinical implications. Per our request, OSH retrospectively performed a pre-transfusion DAT, which was negative, and an AHG crossmatch of the pre-transfusion sample. The results showed that the RBC transfused at OSH on Day 1 were incompatible (1+) and those transfused on Day 2 after O+ platelet transfusion were compatible (Fig. 1). This confirmed that the eluted antibodies were not passively transferred from the platelet transfusion but were rather isoagglutinins from the patient's own plasma of her original blood type O. Chimerism studies indicted the presence of only 25% donor CD3 and 30% donor myeloid cells. Further studies at our institution confirmed the hemolysis to be due to anti-A/A,B and not anti-Goa. Antibody titers of the patient's plasma with A1 and A2 cells were low (1) and negative, respectively. The titer of the eluate with A1 cells and B cells was 4 and 2, respectively. The crossmatch of the patient's plasma with A1 cells was negative at immediate spin and 37oC but positive at the IgG phase, which explains the negative crossmatch at immediate spin at OSH. We believe that the exposure of the 2 incompatible A+ RBC at OSH prompted an anamnestic response, causing the hemolysis of the transfused RBC. Subsequently, the patient required the transfusion of 3 additional RBC. Due to the presence of positive DAT developed after 24 hours of transfusion (on Day 3), the positive elution test, inadequate rise of post-transfusion Hb level and rapid fall in Hb back to the concentration pre-transfusion (Fig. 1), this reaction is best classified as a definitive DHTR in accordance with the CDC hemovigilance guidelines. Conclusion:This case is a warning for the perfect storm from the combination of HPC transplantation and SCD. Our patient had a history of transplantation for SCD and clinically significant alloantibodies. OSH blood bank was not aware of her immunohematologic history, and she received incompatible RBC units that were crossmatched at immediate spin only. She subsequently developed a DHTR which was clinically significant, requiring blood transfusion. This is a good reminder of the importance of good communication between clinicians and the transfusion services. The need for caution when using electronic crossmatch or immediate spin is also important, especially in this era of transplantation for SCD. The absence of RBC antibodies cannot be assumed when a transfusion history is lacking. Increasing awareness, prevention and early recognition and treatment are essential to avoid the potential fatal complication of hemolytic transfusion reactions. Disclosures No relevant conflicts of interest to declare.

Incomplete Complement Inhibition in Patients with PNH on Eculizumab - 5 Year Experience from the National PNH Service Leeds

Background Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare acquired disorder characterised by intravascular hemolysis and thrombosis. Patients with symptomatic PNH are commenced on the complement inhibitor eculizumab (600mg weekly for 5 weeks then 900mg 2 weekly). This monoclonal antibody targets C5 in the complement cascade, halting terminal complement activation thus inhibiting intravascular hemolysis. In some patients intravascular hemolysis is not adequately controlled on the standard regimen. Patient symptoms, transfusion requirements and raised Lactate dehydrogenase (LDH) levels are indicators for suboptimal control of PNH and review of eculizumab dosing. The 50% hemolytic complement (CH50) test is a functional assay assessing capability of serum complement components of the classical pathway to lyse sheep red blood cells pre-coated with rabbit anti-sheep red blood cell antibody. Patients with complement inhibited PNH should demonstrate absent lysis. As the test is expensive and difficult to organise, we tested if incomplete complete blockade as determined by CH50 activity would be better to confirm under-dosing than LDH value. Methods The Leeds (UK) PNH National Service reviewed patients who underwent CH50 assay between January 2015 and March 2020. All patients were on eculizumab with clinical concerns regarding suboptimal control of PNH. Patients receive eculizumab infusions intravenously every 14 days and routine follow up from the PNH Service. Serum samples were obtained 24 hours prior to infusions for CH50 assay; LDH values were routinely collected. Complete complement blockade was defined by &amp;lt;10% CH50 activity; intravascular hemolysis was indicated by LDH value &amp;gt;1.5x upper limit of normal (ULN). Confidence intervals were set at 95% and significance set at p&amp;lt;0.05. Results In the study period, 327 tests (median 2, range 1 - 8) were carried out in 146 patients (median age 54 years, range 16 - 89; 74 female). 81% (265) were successful; 19% (62) were unsuccessful due to processing errors. Of the successful tests, 74% (197 in 127 patients) indicated complete complement blockade and 26% (68 in 38 patients) indicated incomplete blockade. Of the patients with incomplete blockade, 68% (26) demonstrated complete blockade on repeat testing and 32% (12) had their eculizumab dose increased. Clinical symptoms of under-dosing in the 12 patients requiring a dose increase included increased transfusion requirements and/or breakthrough hemolysis (7), pregnancy (2; both returned to 900mg post pregnancy) and significant lethargy (3). Of the patients requiring a dose increase, 3 were on 1200mg before 2015; their dose was increased to 1500mg. Repeat testing was carried out in 10/12 patients after dose increase; 8 indicated complete blockade; 2 patients were incompletely blocked at 1200mg and received a further dose increase to 1500mg. Further testing indicated complete blockade in 1 patient; 1 required a 3rd dose increase to 1800mg due to incomplete blockade and ongoing transfusion requirement. Corresponding LDH values were analysed; median LDH for the complete blockade group was 1.16xULN (range 0.54 - 2.16) and 1.28xULN (range 0.76 - 2.38) for the incomplete blockade group. LDH values were not significantly higher in the incomplete blockade group compared to the complete blockade group, p=0.08. There was no significant difference in LDH values pre- and post-dose increase, p=0.38 (Figure 1); median pre-dose increase LDH 1.14xULN; median post-dose increase LDH 1.13xULN. Correlation coefficient shows that CH50 activity was positively correlated with LDH value, r(123)=0.18, p=0.04. Conclusion We report the effective utilisation of CH50 analysis where there is clinical concern of suboptimal control of PNH. All patients demonstrating hemolytic activity on CH50 assays indicated subsequent complement blockade following increase of eculizumab dose. Increasing eculizumab is costly requiring robust evidence of suboptimal complement inhibition; a positive correlation between CH50 activity and LDH values was shown however this is not sufficient to guide clinical decisions. LDH values of the incomplete blockade group were not significantly higher than those with complete blockade, suggesting the use of LDH values as an assessment of complement inhibition in patients with ongoing symptoms or transfusion requirements is not sufficient to guide eculizumab dose increases. Disclosures Munir: Alexion: Honoraria; F. Hoffmann-La Roche: Consultancy, Other: Medical writing support, furnished by Scott Battle, PhD, of Health Interactions, was funded by F. Hoffmann-La Roche Ltd, Basel, Switzerland. Pike:Apellis: Research Funding. Arnold:Alexion Pharmaceuticals: Honoraria. Hillmen:AstraZeneca: Consultancy, Speakers Bureau; Alexion: Consultancy, Research Funding, Speakers Bureau; Acerta: Other: Financial or material support; Roche: Consultancy, Other: Financial or material support, Research Funding, Speakers Bureau; AbbVie: Consultancy, Other: Financial or material support, Research Funding, Speakers Bureau; Pharmacyclics: Other: Financial or material support, Research Funding; Janssen: Consultancy, Other: Financial or material support, Research Funding, Speakers Bureau; Apellis: Consultancy, Research Funding, Speakers Bureau; Gilead: Other: Financial or material support, Research Funding. Griffin:Alexion Pharmaceuticals: Honoraria, Other: Conference Support; Biocryst: Membership on an entity's Board of Directors or advisory committees.

Effects of Maternal Immune System Status on Neonate’s Immune System

Background: This study evaluated the effects of the maternal immune system stimulation or suppression during the pregnancy on the development of the neonate’s immune system.Methods: A total of 20 female rats were divided into four groups. The groups were treated using Leishmania major, Salmonella typhimurium, Tacrolimus, and sterilized normal saline. The animals were mated after 3-time treatments. The neonate’s humoral immune response, total body, thymus, liver, spleen weight, and histology were determined in this study.Results: The spleen’s mean weight of the two-month-old samples showed a significant reduction in the Salmonella group; in addition, the Tacrolimus group had a significant reduction in liver mean weight. The Salmonella and Tacrolimus groups showed a significant reduction (P≤0.05) in the anti-sheep red blood cells antibody titer.Conclusion: Stimulation or suppression of the immune responses during the pregnancy has significant effects on the neonate’s immune responses, spleen, liver, and thymus development.