Red Cell Antibodies Research Articles

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 <10% CH50 activity; intravascular hemolysis was indicated by LDH value >1.5x upper limit of normal (ULN). Confidence intervals were set at 95% and significance set at p<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.

PREVALENCE OF IRREGULAR RED CELLANTIBODIES IN HEALTHY BLOOD DONORS ATTENDING A TERTIARY CARE HOSPITAL IN SOUTH INDIA

Introduction: Red cell antibodies that are found normally in human serum are considered naturally occurring and those are anti A and anti B. All other antibodies directed against RBC antigens are considered “unexpected or irregular". Aim: This study is aimed to evaluate the prevalence of the anti-red blood cell antibodies among healthy blood donors. Material and Methods: Antibody screening and identification was done using commercially available 3 cell and 11 cell reagent cells (0.8% Surgiscreen, Ortho Clinical Diagnostics Limited, USA and Low ionic Strength Saline Ortho Bliss with AHG Cassettes) in antihuman globulin phase. Results: A total of 36,684 donors were screened for the presence of irregular erythrocyte antibodies. Among these donors, twenty donors showed presence of alloantibodies in their serum (0.054%). Most frequent alloantibodies identified were from Lewis blood group system. The results showed statistically a higher prevalence of RBC alloantibodies in males than in females. Conclusion: Screening for presence of alloantibodies in donor blood is important to provide compatible blood products and to avoid transfusion reactions.

Toward Monocyte HLA-DR Bedside Monitoring: A Proof-of-Concept Study.

Decreased expression of human leukocyte antigen-DR on monocytes (mHLA-DR) is recognized as the most appropriate marker for the monitoring of immune alterations in septic patients and critically ill subjects. Its measurement has been established for years by flow cytometry, but remains under-used due to pre-analytical constraints. The objectives of the present work were to develop a rapid and robust one-step protocol. A novel, simplified protocol has been developed to measure mHLA-DR in whole blood using flow cytometry. It is a one-step procedure that includes red cell lysis, antibodies, and fixative reagents. It has been compared to the standardized routine protocol in two consecutive cohorts of septic shock patients (n = 37). Finally, the protocol was applied to a few subjects in point-of-care settings, by collecting capillary blood from fingerpricks. Strong correlation was observed between the one-step method and routine protocol in 24 patients. After testing several stabilizing agents, the procedure was further optimized by adding a low-dose formaldehyde to the stain and lyse solution. This improved method was tested in a second cohort of 13 patients, and again strongly correlated to the routine protocol. Finally, the fingerprick and venous puncture samples were shown to provide similar results. The present work demonstrates the feasibility of a bedside protocol for flow cytometry measurement of mHLA-DR in critically ill subjects. This helps overcome pre-analytical constraints previously identified, which have limited wider use of this biomarker in intensive care units. In addition, preliminary results from fingerprick samples are promising.

Distribution of maternal red cell antibodies and the risk of severe alloimmune haemolytic disease of the foetus in a Chinese population: a cohort study on prenatal management

BackgroundHaemolytic disease of the foetus and newborn (HDFN) is the most common aetiology of haemolytic anaemia and hyperbilirubinaemia in foetuses and neonates. Studies on the distribution of antibodies that cause haemolytic disease of the foetus (HDF) in China are limited, and the effects of multiple antibodies on the severity of HDF need further evaluation.MethodsAn observational cohort study from January 2005 to December 2019 was conducted in two hospitals affiliated with Sun Yat-sen University. Maternal red cell alloimmunization was identified by the Guangzhou Blood Centre. In total, 268 pregnant woman-foetus pairs were divided into four groups according to the type of maternal alloantibodies: anti-D, anti-D combined with other antibodies, other single-antibody and other multiple antibodies. The obstetric history, antibody characteristics, incidence of severe HDF and foetal outcomes were collected and compared. Logistic regression analysis of the risk factors for HDF and survival analysis of the severe HDF-free interval were conducted.ResultsAnti-D was the most common cause of HDF, followed by anti-M. No anti-K- or isolated anti-c-associated HDF was found. The incidence of severe HDF was higher in the group with anti-D combined with other antibodies than in the group with anti-D alone (P = 0.025), but no significant difference was found in haemoglobin level and reticulocyte count in the anaemic foetuses between these two groups. Foetuses in the other single-antibody group had a lower reticulocyte count (P = 0.007), more IUTs (P = 0.007) and an earlier onset of severe HDF (P = 0.012). The maximum antibody titre was significantly lower in the other single-antibody group than in the anti-D group (P < 0.001). A high maternal antibody titre (P < 0.001), multiple affected pregnancies (P < 0.001) and other single-antibody (P = 0.042) were independent risk factors for HDF. A higher reticulocyte count (P = 0.041) was an independent risk factor for severe HDF in anaemia foetuses affected by Rh(D) alloimmunization.ConclusionsThe distribution of HDF-associated antibodies in China is different from that in Western countries. Other single non-Rh(D) antibodies could increase the risk of HDF, and anti-D combined with other antibodies would not influence the severity of foetal anaemia compared with anti-D alone.

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.

Immunosuppressive properties of cytochalasin B-induced membrane vesicles of mesenchymal stem cells: comparing with extracellular vesicles derived from mesenchymal stem cells

Extracellular vesicles derived from mesenchymal stem cells (MSCs) represent a novel approach for regenerative and immunosuppressive therapy. Recently, cytochalasin B-induced microvesicles (CIMVs) were shown to be effective drug delivery mediators. However, little is known about their immunological properties. We propose that the immunophenotype and molecular composition of these vesicles could contribute to the therapeutic efficacy of CIMVs. To address this issue, CIMVs were generated from murine MSC (CIMVs-MSCs) and their cytokine content and surface marker expression determined. For the first time, we show that CIMVs-MSCs retain parental MSCs phenotype (Sca-1+, CD49e+, CD44+, CD45−). Also, CIMVs-MSCs contained a cytokine repertoire reflective of the parental MSCs, including IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12(p40), IL-13, IL-17, CCL2, CCL3, CCL4, CCL5, CCL11, G-CSF, GM-CSF and TNF-α. Next, we evaluated the immune-modulating properties of CIMVs-MSCs in vivo using standard preclinical tests. MSCs and CIMVs-MSCs reduced serum levels of anti-sheep red blood cell antibody and have limited effects on neutrophil and peritoneal macrophage activity. We compared the immunomodulatory effect of MSCs, CIMVs and EVs. We observed no immunosuppression in mice pretreated with natural EVs, whereas MSCs and CIMVs-MSCs suppressed antibody production in vivo. Additionally, we have investigated the biodistribution of CIMVs-MSCs in vivo and demonstrated that CIMVs-MSCs localized in liver, lung, brain, heart, spleen and kidneys 48 h after intravenous injection and can be detected 14 days after subcutaneous and intramuscular injection. Collectively our data demonstrates immunomodulatory efficacy of CIMVs and supports their further preclinical testing as an effective therapeutic delivery modality.

The impact of pre-existing HLA and red blood cell antibodies on transfusion support and engraftment in sickle cell disease after nonmyeloablative hematopoietic stem cell transplantation from HLA-matched sibling donors: A prospective, single-center, observational study.

BackgroundHematopoietic stem cell transplantation (HSCT) is curative for patients with sickle cell disease (SCD). Prior to HSCT, patients with SCD commonly receive RBC transfusions with some becoming RBC or HLA alloimmunized. This alloimmunization may impact post-HSCT transfusion requirements and donor engraftment.MethodsThe study population included patients with SCD transplanted on a single-center nonmyeloablative, HLA-matched sibling HSCT trial at the National Heart, Lung, and Blood Institute (NHLBI) who had a pre-HSCT sample available for HLA class I antibody testing. We evaluated transfusion requirements and engraftment outcomes comparing patients with and without pre-existing HLA and RBC antibodies.FindingsOf 36 patients studied, 10 (28%) had HLA class I antibodies and 11 (31%) had a history of RBC alloantibodies. Up to day +45 post-HSCT, patients with HLA antibodies received more platelet transfusions (median 2.5 vs 1, p = 0.042) and those with RBC alloantibodies received more RBC units (median 7 vs 4, p = 0.0059) compared to respective non-alloimmunized patients. HLA alloimmunization was not associated with neutrophil engraftment, donor chimerism, or graft rejection. However, RBC alloimmunization correlated with a decreased donor T cell chimerism at 1 year (median 24% vs 55%, p = 0.035).InterpretationPre-existing HLA and RBC alloantibodies are clinically significant for patients undergoing HLA-matched nonmyeloablative HSCT. Testing for both HLA and RBC antibodies is important to help estimate transfusion needs peri‑HSCT. The association of lower donor T cell chimerism and pre-existing RBC alloantibodies needs further investigation.FundingNIH Clinical Center and NHLBI Intramural Research Program (Z99 CL999999, HL006007–11) and the Thrasher Research Fund.

MON-279 Correlation Between Haemolitic Complement Activity (CH50) and Growth Hormone Response to Stimulation in Adult Growth Hormone Deficiency: Preliminary Data

It is known that GH, directly or via IGF-1 activity, influences many aspects of immune response; both humoral and cellular branches are modulated, but no data are available about complement function. CH50 is a screening assay for the activation of the classical complement pathway and it is sensitive to the reduction, absence and/or inactivity of any component of the pathway. The CH50 tests the functional capability of serum complement components of the classical pathway to lyse sheep red blood cells (SRBC) pre-coated with rabbit anti-sheep red blood cell antibody (haemolysin). On the other hand, a low inflammation is present in GH deficiency (GHD) and it is related to cardiovascular risk of such situation, also in partial forms.Therefore, we performed a cohort study in a group of adult GHD patients evaluating CH50 levels to further explore the pattern of inflammatory markers in this condition.We included 17 patients with total GHD (GH peak after stimulation with GHRH+arginine <9 ng/ml with BMI<30 or <4 ng/ml with BMI≥30 Kg/m2; n=15) or partial GHD (peak between 9 and 16 ng/ml with BMI<30 Kg/m2 n=2) with mean±SEM BMI 27.7±2.6 kg/m2 and mean±SEM age 52.5±2.6 ys. The etiology of GHD, assessed by MRI, was: primary empty sella (n=7); post-surgical (n=1) pituitary adenoma (n=4); idiopathic (n=4), pineal cyst (n=1); CH50 has been assayed by turbidimetric method. Mean±SEM CH50 of entire cohort was 50.75±2.5 U/l (normal range 12.5-100 U/ml); however, a significant inverse correlation was observed between GH AUC and CH50 levels (Spearman r=-0.49; p=0.04).This datum joint to our previous observations about increased free light chains of immunoglobulins in GHD, substantiating the hypothesis of chronic low-grade inflammation affecting this condition, which in turn could negatively influence GH secretion. These data could be of interest especially in patients recognized as “idiopathic” GHD, where no pituitary morphologic alterations or anamnestic information (previous surgery, trauma or irradiation) were found. However, these data cannot be conclusive and further studies are needed to establish the causal relationships between these parameters, also in a greater cohort of patients.

Short-term outcomes following intrauterine transfusions for fetal anaemia: A retrospective cohort study.

Intrauterine transfusion (IUT) is the accepted standard for management of severe fetal anaemia. However, fetal transfusion may be associated with procedural complications such as fetal demise. There is a paucity of recent data on outcomes for severe fetal anaemia in Australia as compared with published outcomes from large international centres. To review the indications for and the procedural, obstetric and neonatal outcomes following intrauterine transfusion for fetal anaemia conducted at the New South Wales Fetal Therapy Centre (NSW FTC). Retrospective cohort study conducted between 2005 and 2017 of the outcomes of 85 IUT procedures (39 pregnancies). Data collected included maternal demographics, procedural and obstetric details and short-term neonatal outcomes. Complete outcome data were available for 36/39 pregnancies. Red cell antibodies were the main indication for fetal transfusion (79%, predominantly D, Kell and other Rhesus antibodies) with parvovirus accounting for 8% of procedures. IUT was associated with a pregnancy loss rate of 1.2%/procedure, amounting to 2.6%/pregnancy. Fetal losses were limited to those complicated by hydrops prior to IUT (3/10 hydrops vs 0/26 non-hydropic; P=0.003). Procedural outcomes at NSW FTC compare favourably with international centres (1.1-8.7% procedural loss rate). However, this comparison is limited, as no procedures were performed during the last 24months of the study. Given this, a nationwide audit is recommended to help guide appropriate centralisation of procedures and thereby maximise clinician experience and outcome.

Comparison of the Efficiency of BLUP and GBLUP in Genomic Prediction of Immune Traits in Chickens.

Simple SummaryWith the rapid development of the poultry industry, outbreaks of certain avian diseases such as avian influenza, Newcastle disease, and salmonellosis can cause severe loss to local economies. An effective method to avoid this problem may be developing resistant lines on the basis of immune response traits. In our study, when the number of genotyped reference animals was small, the traditional pedigree-based method (BLUP) was more efficient than the genetic linear unbiased prediction of genomes (GBLUP) method in predicting the genetic parameters of sheep red blood cell antibody titer (SRBC), the ratio of heterophils to lymphocytes (H/L), the spleen immune index (SII) and the spleen weight at 100 d (SW) in Beijing oil chickens.Poultry diseases pose a large threat to poultry production. Selection to improve immune traits is a feasible way to prevent and control avian diseases. The objective of this study was to investigate the efficiency of estimation of genetic parameters for antibody response to avian influenza virus (Ab-AIV), antibody response to Newcastle disease virus (Ab-NDV), sheep red blood cell antibody titer (SRBC), the ratio of heterophils to lymphocytes (H/L), immunoglobulin G (IgG), the spleen immune index (SII), thymus immune index (TII), thymus weight at 100 d (TW) and the spleen weight at 100 d (SW) in Beijing oil chickens, by using the best linear unbiased prediction (BLUP) method and genomic best linear unbiased prediction (GBLUP) method. The phenotypic data used in the two methods were the same and were from 519 individuals. With the BLUP model, Ab-AIV, Ab-NDV, SRBC, H/L, IgG, TII, and TW had low heritability ranging from 0.000 to 0.281, whereas SII and SW had high heritability of 0.631 and 0.573. With the GBLUP model, all individuals were genotyped with Illumina 60K SNP chips, and Ab-AIV, Ab-NDV, SRBC, H/L and IgG had low heritability ranging from 0.000 to 0.266, whereas SII, TII, TW and SW had moderate heritability ranging from 0.300 to 0.472. We compared the prediction accuracy obtained from BLUP and GBLUP through 50 time 5-fold cross-validation (CV), and the results indicated that BLUP provided a slightly higher accuracy of prediction than GBLUP in this population.

Improved health care utilization and costs in transplanted versus non-transplanted adults with sickle cell disease.

Patients with sickle cell disease (SCD) have access to fewer health care resources and therapies compared to other diseases, which contributes to increased morbidity and health care utilization. We compared health care utilization (inpatient hospital days, emergency care visits) and health care-related costs between SCD adults that underwent hematopoietic stem cell transplantation (HSCT) using a nonmyeloblative conditioning regimen versus those referred for HSCT but did not proceed due to lack of an HLA-matched sibling donor, denial by insurance, red blood cell antibodies to the potential donor, or declining further evaluation. Between 8/2011 and 4/2016, 83 SCD patients were referred for allogeneic HSCT and 16 underwent the procedure. The HSCT and non-HSCT groups were similar by age, sex, prior SCD-related therapy and complications. Compared to pre HSCT, significantly fewer inpatient hospital days (median of 1 versus 22 days, P = 0.003) and emergency care visits (median of 1 versus 4 visits, P = 0.04) were observed by the 2nd year post-HSCT. Similar results were observed in comparison to the standard-of-care group (median of 1 versus 12 hospital days, P = 0.002; median of 1 versus 3 emergency visits, P = 0.03). Lower health care costs were observed by the 2nd year post-HSCT (median of $16,281 versus $64,634 pre-HSCT (P = 0.01) and versus $54,082 in the standard-of-care group (P = 0.05). A median reduction of -$20,833/patient/year (IQR, -$67,078-+$4,442/patient/year) in health care costs compared to pre-HSCT was observed in the 2nd year post-HSCT. In conclusion, allogeneic HSCT leads to improvements in health care utilization and costs compared to standard-of-care therapy in high-risk SCD adults.

Prevalence of red blood cell antibodies in whole blood donors: A single-centre experience in north India.

Background & objectives:Blood transfusion therapy involves multiple steps to ensure selection of safe blood component for transfusion. This includes testing for infectious markers, full ABO compatibility, free from any clinically significant red cell antibodies and acceptable donor's red cell survival rates without destruction of recipient's red cells. The red cell antibodies present in healthy blood donors can cause severe haemolytic transfusion reaction, especially in massive blood transfusion recipients and paediatric patients. Hence, screening of red cell antibodies in donor blood is important to provide compatible blood products and to avoid haemolytic transfusion reactions in susceptible patient population. This study was planned to assess prevalence, aetiology and type of unexpected red cell antibodies in a large number of whole blood donor population in north India.Methods:This three-year prospective observational study included blood donor samples for antibody screening from January 2015 to December 2017. A total of 166,803 healthy blood donors including 156,128 (93.6%) males and 10,675 (6.4%) females were screened.Results:The prevalence of red cell antibodies was 0.17 per cent in our donor population. Of the total 286 donors with red cell antibodies, 248 (86.7%) had alloantibodies, 30 (10.5%) had autoantibodies and eight donors (2.8%) showed positive antibody screening with inconclusive results.Interpretation & conclusions:Alloimmunization to red cell antigens is a challenging task for current transfusion practices. The antibody screening in blood donors may improve the quality and safety of blood transfusion in the recipients. It also reduces the risk of complications from incompatible blood transfusions.

Frequency and clinical significance of red cell antibodies in pregnancy - A prospective study from India.

For appropriate management of hemolytic disease of the fetus and newborn (HDFN), it is important to detect irregular red cell antibody in the antenatal period. Though it is a simple one-step method, it is not part of routine antenatal screening in many developing countries. To reiterate the importance of antenatal antibody screening, we have assessed the frequency and clinical significance of irregular red cell antibodies in our patient population. A prospective study was carried out from October 2013 to May 2015 at a tertiary care center from south India. All antenatal samples received by the laboratory for red cell antibody screening were screened using a commercial three-cell screening panel. Antibody identification along with further Immunohematological techniques as required were performed for cases with positive screening results. Neonates of the alloimmunized cases were followed up to determine the clinical significance of the antibody. A total of 2336 antenatal mothers were screened for red cell antibodies. The overall rate of alloimmunization in the study group was 2.27%. Alloimmunization rate among RhD-negative pregnancies was 6.9%. Other than anti-D (49%), we identified anti-D + anti-C (5%), anti-G (5%), anti-c (5%), anti-E (2%), anti-e (2%), anti-H (Bombay phenotype) (7%), anti-M (2%), anti-Lea (2%), anti-Leb (12%), and autoantibodies (9%) in the maternal serum. Anti-D, anti-D + anti-C, anti-G, anti-c, and anti-H were found to be clinically significant in this study. This study showed that 1 in 125 RhD-positive pregnancies can develop red cell alloantibodies. Hence, implementing routine antenatal antibody screening irrespective of RhD status is essential.

Red blood cell alloimmunization in Iran: A Comprehensive review of the literature.

BACKGROUND:Alloimmunization is an immune response against foreign antigens which introduced into the body through transfusion, pregnancy, or transplantation. This phenomenon is a big challenge in patients, which require regular transfusions. In the current study, we tried to have a comprehensive review on the status of alloimmunization in Iran. For this purpose, we searched for papers investigating alloimmunization in transfusion-dependent patients and also in patients with no regular transfusions who are candidate for surgery or who need blood.METHODS:We searched PubMed, Google Scholar, SID, and MAGIRAN databases using the following keywords: “blood transfusion,” “alloimmunization,” “alloantibodies,” “irregular antibodies,” “red cell antibodies,” and “Iran.” No limitation for the date of publication and language of the papers was defined. All the identified records were then screened for the relevance and duplication.RESULTS:A total of 22 papers were included in this study. All of the studies were conducted from 1999 to 2016 and providing alloimmunization data from different cities all over of Iran. In general, the results showed that the most prevalent alloantibodies are anti-Kell (anti-K antigen) and anti-Rh system, mainly anti-E, anti-D, anti-C, and anti-c.CONCLUSION:Anti-Kell and anti-Rh antibodies are the most prevalent antibodies responsible for alloimmunization in Iranian population.

Frequency of alloantibody with their specification among multitransfused patients

Background and Objectives: Alloimmunization is a very common clinical problem in transfusion-dependent patients but rarely detected in Bangladesh. The risk of alloimmunization is especially high in patients who receive repeated transfusion, i.e., thalassemia patients. The objective of this study was to investigate the seroprevalence and specificity of red blood cell antibodies in multitransfused thalassemic patients. Methods: This cross-sectional study was conducted at a tertiary care referral center from January 1, 2013, to March 31, 2016. Blood specimens were sent from different facilities and also from daycare transfusion center of the same when cross-match difficulties occur. When the Coomb's test showed positive result, then Rhesus, Kell, Kid, Duffy, and Lewis blood group typing were done according to the patients' need. Serum was used to identify the presence of alloantibody by the indirect Coomb's test with known cell panels. An autocontrol, positive and negative control for each specimen was incorporated to detect autoantibody and correctness of the procedure done. We performed a simple percentage to evaluate the analysis. Results: Of 1286 cases, alloantibody was detected in 334 (25.97%) cases. Among the 334 cases, 80 (23.95%) cases were followed up by antibody identification. The remaining 254 cases were referred cases with insufficient history and were dropped from the study. The male-to-female ratio was 1:2.2. The age group of 21–30 years showed the maximum antibody specificity (7.48%). Among the 80 samples with alloantibodies, Rh antibodies were noted in 80% (64) samples. Other antibodies detected belong to Kell, Kid, Duffy, and Lewis systems. Conclusion: Multitransfused (thalassemic) patients are more vulnerable to develop alloantibody. Therefore, routine antibody screening of donors and patients and the provision of antigen negative blood is recommended.

BOOK REVIEW: Red Cell Antigens and Antibodies

BOOK REVIEW: Red Cell Antigens and Antibodies

Analysis of red cell alloimmunization in multi transfused patients at a Tertiary care teaching hospital.

Background:Red blood cell (RBC) alloimmunization is an immune response against foreign RBC antigens; this generally occurs after sensitization due to multiple blood transfusions and pregnancies. Antibody detection plays a critical role in transfusion medicine as it can detect irregular or unexpected antibodies. This study was done to know the frequency and specificity of unexpected red cell antibodies in the multitransfused patients.Materials and Methods:This prospective study was done in the Department of Immuno-Haematology and Blood Transfusion. Antibody screening of 100 multitransfused patients with initial negative antibody screen was carried out prior to compatibility testing and followed for a period of 12 months for each transfusion. Depending on the results, patients were given corresponding antigen-negative blood units.Results:In this study, the rate of alloimmunization was 7%. Total number of samples that were positive for irregular alloantibodies were 4 of 54 cases of thalassemia, that is, 7.4%, whereas 3 of 40, that is, 7.5%, cases of solid malignancies developed alloantibodies. None of the patients of chronic kidney disease formed any alloantibody. Anti-K antibody was the most frequent antibody detected in 3 of 7, that is, 42.8% patients. Anti-E was the second most frequent antibody observed in 2 of 7, that is, 28.57%. However, anti-c and anti-M were detected in one each of 7, that is, in 14.28% each.Conclusion:It is concluded here that red cell alloimmunization should not be overlooked in multitransfused patients. To avoid the effects of alloimmunization, routine RBC antibody screening at set time intervals after transfusion should be performed.

Frequency of Red Blood Cells Alloimmunization in Thalassemia Patients at King Abdulaziz University Hospital in Jeddah, Saudi Arabia

The aim of the study is to assess the alloimmunization rate to red blood cell in thalassemia patients at King Abdulaziz University Hospital. Thalassemia is the most common genetic disorder worldwide that represents a major public health problem and requires long life blood transfusion to the patients as the main treatment. Alloimmunization to the transfused red blood cell can cause hemolytic transfusion reactions and significantly complicate transfusion therapy. Screening and identification of alloantibodies and transfusion of extended phenotyped blood can minimize these risks. A retrospective study was conducted on 134 thalassemia patients at King Abdulaziz University Hospital in Jeddah. Patients’ samples were subjected to red cell typing, antibody screening and identifi cation of red blood cell antibodies. Alloimmunization in thalassemia patients was 20.15%; antibodies were mainly to the Rh and Kell blood group systems, the highest rate was for anti-E (32.4%) followed by anti-K (21.6%). Alloimmunization rate was the highest in the age group from &gt; 10 – 20 years (40.7%). Red cell alloimmunization is a frequent event among thalassemia patient. A national protocol for screening and identifying of the red cell alloantibodies and transfusion of phenotype blood is required for proper management of these patients.

Diagnostic value of laboratory monitoring to predict severe hemolytic disease of the fetus and newborn in non-D and non-K-alloimmunized pregnancies.

Pregnant women are routinely screened for red blood cell (RBC) antibodies early in pregnancy. If RBC-alloantibodies are detected, repeated laboratory testing is advised to timely identify pregnancies at high risk for severe hemolytic disease of the fetus and newborn (HDFN). We assessed for RBC alloantibodies, other than anti-D or anti-K, cut-offs for the titer and the antibody dependent cellular cytotoxicity (ADCC) test to select high-risk cases. To advise on test repeat intervals, and to avoid unnecessary testing, we evaluated the chance for exceeding the cut-offs for Rh antibodies other than anti-D, Jk, Fy, and S/s antibodies. Diagnostic value of antibody titer and ADCC test was determined with data from a prospective index-cohort study, conducted in 2002-2004. Laboratory test outcomes were from a recent observational cohort (2015-2016). A titer cut-off of ≥16 showed a sensitivity of 100% (95% CI:73-100%) and a positive predictive value (PPV) of 17% (95% CI:14%-20%). The percentage of pregnancies reaching a titer above the cut-off of ≥16 varied from 0% for anti-Jka /Jkb (n = 38) to 36% for anti-c (n = 97). The ADCC test showed no cut-off with a 100% sensitivity. However, in cases with a titer ≥16 and an ADCC test ≥30% a PPV of 38% was obtained to detect severe HDFN. A titer cut-off of ≥16 is adequate to detect all cases at risk for severe HDFN; the ADCC test may add a more accurate risk estimation. Repeated testing is recommended in pregnancies with anti-c. In pregnancies with other Rh antibodies a repeated test in the third trimester is recommended.

Prevalence and Haemolytic Significance of Red Cell Antibodies among Dangerous Universal Donors in a Tertiary Care Hospital in South India

Background and Aims: A subgroup of group O individuals called ‘dangerous universal donors’ have immune (IgG) anti A and anti B antibodies which are active at 37˚C and capable of reacting with the red cells and causing lysis. The aim of this study was to find the prevalence of dangerous O group among the voluntary donor population and to assess the relation between the degree of haemolysis and the antibody titre. Materials and Methods: Group O donors excepting those with history of transfusion or pregnancy were included in the study. The serum samples were tested for haemolysins as per standard procedure. The degree of haemolysis was graded and strongly haemolytic samples were further characterised for the type of immunoglobulin class after treatment with dithiothretiol. The results were coded and analysed using SPSS software. Results: The age of the donors in this study ranged from 18 to 56 years. Majority were males. The prevalence of dangerous O group in our study population was found to be 10.75%. Within the dangerous O group samples, the titre of anti B IgG antibody was found to be higher than anti A IgG antibody. Titres for both anti A and anti B IgG antibodies ranged from 1:2 to 1:64. Conclusions: A simple screening for donor haemolysins will help in identification of strongly haemolytic samples, which are likely to have high titres of IgG, particularly anti A antibody. This will prevent transfusion of blood containing high titres of immune anti A and anti B antibodies to non O group recipients.