Rate Of Alloimmunization Research Articles

Predictors, Risk Factors and Outcomes of Patients with SAA with Anti-HLA Class I Antibodies Treated with Immunosuppressive Therapy

Introduction: Platelet refractoriness, defined as persistently inadequate post-transfusion count increments, can be immune or non-immune. Human leukocyte antigen (HLA) Class I antibodies are the usual immune cause. The presence of HLA platelet antibodies (Abs) in hematologic disease has been associated with poorer clinical outcomes, graft failure in hematopoietic stem cell transplant, increased bleeding, and decreased survival. In immune severe aplastic anemia (SAA), literature addressing prophylactic transfusion of platelets is lacking, but most recommend transfusion with bleeding at a count <10 or <20 K/ µL if febrile or during ATG (anti-thymocyte globulin) administration. Chronic platelet transfusion is a risk for development of HLA Abs; nevertheless, some chronically transfused patients do not become alloimmunized while others do so rapidly, even after a single platelet transfusion. We analyzed our SAA patients to document the rate of HLA alloimmunization and its possible association with disease characteristics and outcomes after immunosuppressive therapy (IST). Methods: Clinical records from 444 SAA patients treated at the NIH Clinical Center from 2000 to 2022 were retrospectively reviewed. Demographics included: age, sex, HLA Class 1 Abs status, platelet refractoriness, peripheral blood counts, PNH clone, treatment and relapse, evolution to myeloid malignancy or chromosome abnormality, and overall survival (OS). Patients were tested for HLA Abs if they met 1 or more of 3 clinical criteria: 1) history of HLA Abs; 2) history of or current platelet transfusion refractoriness; 3) work up for bone marrow transplantation. Clinical refractoriness was defined as lack of platelet increment of >5 K/µL or a corrected count increment (CCI) of >5 K/µL. Patient lacking evidence of refractoriness were presumed anti-HLA negative and not tested, and those that tested negative for HLA Ab were transfused platelets unmatched for any HLA antigens. Logistic regression was used to analyze associations between age, sex, blood counts, PNH clone, and disease severity, and Kaplan Meier curves and Cox proportional hazards model for survival. Data were analyzed using R, and p<0.05 was considered statistically significant. Results: Demographic data were collected for 444 patients (Table.1). HLA Ab testing was performed in 155 patients while 289 didn't meet criteria for testing. Of 444 patients, 99 (22%) tested positive for HLA Class 1 Abs. Seventy-three of 99 patients responded to HLA matched platelets, whereas, 17 remained refractory and for 9 data were unavailable. Univariate analysis predicted male sex to be protective against HLA Abs formation (OR=0.59,p= 0.02), while more severe disease (VSAA, OR= 2.51, p<0.001) and lower baseline blood counts predicted alloimmunization. Low platelet counts (p<0.001) were most significant followed by absolute reticulocyte (ARC) and absolute neutrophil counts (ANC) with p=0.005. PNH was not associated with refractoriness, although data were incomplete. Only HLA Class 1 Ab status and age, and sex were strong predictors of survival in both univariate and multivariate analysis. ANC, ARC, and disease severity were significant predictors of survival in the univariate but not multivariate model. Median time to relapse was 2.4 years with a relapse rate of 36% at median follow-up. Rate of relapse was 46% in alloimmunized patients vs.34% in the Ab negative group, but this difference was not statistically significant (p=0.2). OS for the entire cohort was 84% at median follow up 4 years; HLA Ab-negative patients had a significantly higher OS compared with positive (86% and 75% respectively; p = 0.02). Rates of clonal evolution were also higher in the HLA Ab positive group but not statistically significant (25% vs. 13%, p=0.08). Conclusions: We report a large cohort of IST-treated SAA patients, comparing outcomes with and without HLA alloimmunization. Although SAA patients are usually heavily transfused platelets, we observed a rate of HLA alloimmunization of 22%. OS was decreased in HLA alloimmunized patients. Presence of HLA ab and age were strong predictors of survival. ANC, ARC and disease severity were predictors of survival only in the univariate model. Relapse and clonal evolution may be increased when HLA Abs are present. Overall, the presence of HLA Abs is associated with poorer outcomes in SAA patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A US-Wide Red Blood Cell Alloantibody Exchange Can Decrease Mortality and Produce Cost Savings in the Care of Alloimmunized Patients with Sickle Cell Disease

Introduction: Red blood cell (RBC) alloimmunization occurs after exposure to non-self RBC antigens through transfusion or pregnancy. Alloimmunization rates and consequently delayed hemolytic transfusion reaction (DHTR) mortality in patients with sickle cell disease (SCD) is particularly high. Interest in a blood bank information system vendor-based alloantibody exchange in the United States (US) is growing, though cost concerns exist. To investigate the impact of an exchange that enables alloantibody data-sharing across hospitals, we conducted the first disease simulation of allo-immunized patients with SCD to project lifetime cumulative DHTR-specific mortality without an alloantibody exchange (status quo) versus with a US-wide alloantibody exchange. We then additionally performed a cost-effectiveness analysis to identify whether investing in an alloantibody exchange would be cost-effective, cost saving or neither. Methods: We built a Markov simulation of alloimmunized patients with SCD in the US. Transition probabilities for DHTR incidence and DHTR-specific mortality were informed from the largest prospective (n=311) and retrospective (n=220) studies of DHTR incidence in people living with SCD. Age-, gender- and disease-specific background mortality probabilities were employed. Cumulative probability of DHTR was modeled from age 5, with a lifetime horizon. Costs were assessed from the health system perspective and effectiveness was calculated in quality-adjusted life-years (QALY). QALYs were informed by published lifetime simulation of patients living with SCD and matched controls. These were originally derived from a polynomial fit linking Euroqual-5 Dimensions to the visual analog scale for pain in patients with SCD in several studies. Cost-effectiveness was quantified using an incremental cost-effectiveness ratio (ICER), or net monetary benefits (NMB) if the intervention was found to be cost saving, either way incorporating a cost-effectiveness willingness-to-pay threshold of $100,000/QALY, as recommended practice. We assumed a lifetime operating cost of $10 million for an alloantibody exchange, that no patient with diagnosed DHTR has more than one DHTR recurrence, that an exchange would not be able to prevent all DHTRs (as up to 30% are not associated with a new detectable antibody in SCD), and utilized prior estimates for US allo-immunized population prevalence range of 20-44% for people living with SCD. We validated our estimate for DHTR reduction with that of the 10-year experience in the national Dutch Transfusion Register of Irregular Antibodies and Cross-match Problems (TRIX). We then conducted deterministic and probabilistic sensitivity analyses, varying all parameter estimates +/-20% and capturing uncertainty in all parameters simultaneously over 10,000 Monte Carlo simulations. Results: Base-case lifetime simulation comparing the strategies of implementing an alloantibody exchange versus not yields a decrease in cumulative lifetime DHTR-specific mortality (2.4% vs 5.7%, respectively; Figure 1). The absolute peak probability decrease of having a history of incident DHTR and being alive occurs at age 41 (10.6% vs 27.0%; Figure 1). The strategy of alloantibody exchange implementation accrues 22.08 per-person lifetime discounted QALYs [95% credible interval 22.03-22.12] versus 21.72 without [95% CI 21.61-21.82], corresponding to a per-person QALY increase of 0.357 with exchange implementation. The lifetime population benefit for an alloimmunized population living with SCD in the United States is up to 15,710 QALYs gained. Total lifetime costs accrue $1.0 billion with exchange as compared to $2.5 billion without. This yields population-level cost savings of $1.5 billion USD ($34,091 saved per alloimmunized patient registered in the exchange), with an accrued incremental NMB of $3 billion. In probabilistic sensitivity analysis the former is favored in 100% of 10,000 Monte Carlo simulations. Conclusion: By reducing DHTR-specific mortality, an alloantibody exchange is predicted to be a life- and cost-saving investment for alloimmunized people living with SCD. Although this analysis was limited to SCD, the impact of an alloantibody exchange would also bring benefit to patients who are alloimmunized in the context of diagnoses and states beyond SCD, such as myelodysplastic syndrome, thalassemia, autoimmune conditions, and pregnancy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

SRSF2 or TET2 Mutations in Patients with MDS Predict Increased Red Blood Cell Alloimmunization

INTRODUCTION: Chronic inflammation is associated with increased red blood cell (RBC) alloimmunization. Patients with sickle cell disease (SCD), systemic lupus erythematosus and inflammatory bowel disease, all conditions with increased levels of inflammation, have been shown to be more alloimmunized when compared to the general population. High prevalence rates of RBC alloimmunization have also been observed in patients with myelodysplastic syndrome (MDS). It has recently been shown that an inflammatory microenvironment may be a key driver of MDS pathogenesis. There are a few specific genes recurrently mutated in MDS that have been found to be associated with activation of the innate immune system and formation of the inflammasome, including some involved in epigenetic modification - ASXL1, DNMT3A, EZH2 and TET2 - and spliceosome formation - SF3B1, SRSF2 and U2AF1. The aim of this study was to determine if the genetic mutations driving the inflammatory milieu in MDS could simultaneously be creating an environment that promotes alloimmunization. PATIENTS AND METHODS: We identified patients diagnosed with a myeloid neoplasm, including patients with MDS and acute myeloid leukemia (AML), between 2015 and 2020 on whom a type and screen had been ordered. We recorded the patients’ primary diagnosis, sex, race/ethnicity, age at first sequencing, somatic mutations identified by next generation sequencing (NGS), blood type, antibody screen results, specific alloantibodies and autoantibodies identified, and number of RBC and platelet units transfused. Patients with an autoantibody, a clinically significant alloantibody, or non-specific reactivity with a potential antibody under investigation on their screen were put in the positive antibody screen category, and those with reactivity solely due to Rh immune globulin or monoclonal antibody therapy were put in the negative antibody screen category. Univariate logistic regression was run separately for patients initially diagnosed with AML and those initially diagnosed with a non-AML myeloid neoplasm (MN), using sex, age, race/ethnicity, number of RBC units transfused, and somatic mutation, to determine if any of these variables had a significant association with a positive antibody screen. If quasi-complete separation issues existed, Firth's method for separation was applied to the logistic regression model. All analyses were conducted using a 95% confidence level. RESULTS: Seventy-six patients met inclusion criteria; 44 were male and 32 were female, and ranged in age from 14 to 89 years. The majority of patients were Caucasian (n = 64). Thirty-three patients had an initial diagnosis of AML; 43 were initially diagnosed with a MN, including MDS (n = 36), myeloproliferative neoplasm (n = 2), chronic myelomonocytic leukemia (n = 4) and chronic myeloid leukemia (n = 1). Number of RBC units transfused ranged from 3 - 112 in patients with AML and 0 - 131 in patients with a MN. Thirteen patients with AML had a positive antibody screen (39.4%), compared to 21 patients with a MN (48.8%). Patients with AML most often developed an alloantibody without an accompanying autoantibody (58.3%), while patients with a MN most often developed alloantibodies in addition to autoantibodies (52.4%). Patients with a MN and a SRSF2 mutation had a significantly increased rate of allo- or auto-immunization as compared to patients with AML and a SRSF2 mutation (p-value = 0.035). Similarly, patients with a MN and a TET2 mutation had a significantly increased rate of allo- or auto-immunization as compared to patients with AML and a TET2 mutation (p-value = 0.021). CONCLUSIONS: In patients with a MN, the presence of a SRSF2 or TET2 mutation predicted the presence of at least one allo- or autoantibody. Our data support the hypothesis that genetic mutations involved in formation of the inflammasome may be involved in the increased alloimmunization seen in patients with MDS. Our study of alloimmunization in MDS, and further studies like it, may enable us to predict based on genetic mutations which patients with MDS may be at increased risk for becoming alloimmunized. Similar to prophylactic C, E and K antigen matching that some blood banks employ in patients with SCD to minimize formation of alloantibodies, extended phenotype matching for the most immunogenic antigens could also be considered in patients with MDS and SRSF2 or TET2 mutations to decrease alloimmunization in this patient population.

Alloimmunization to Rh Antigen (D, C, E, C, E) Among Pregnant Women Attending Antenatal Care in South Western Uganda.

Maternal red cell alloimmunization to Rh antigen in pregnant women occurs when the immune system is sensitized by foreign red blood cell surface antigens, in this case fetal red blood cells, inducing an immune response. Various antigens of blood group systems may cause alloimmunization, especially the Rh, Kel, Fy, JK, and MNS systems. This study aimed to determine alloimmunization to the different frequencies of Rh antigen among pregnant women in South Western Uganda. A total of 1369 pregnant women consented and were recruited into a cross-sectional study during their regular antenatal visits during the period August 2020 to July 2021. Samples (4 mL) of anticoagulated and coagulated blood were obtained, and Rh blood grouping including Rh antigen and the indirect antiglobulin test (IAT) was carried out using the agglutination technology of the LISS ID-Card technique in the Ortho Biovue ID-Micro Typing System. Out of 1369 participants recruited to the study, 78 (5.7%) were D-, 1291 were D+, and 134 (9.8%) had alloantibodies. Among those with alloantibodies, 115 (85.8%) were D+ and 19 (14.2%) D-. The percentage alloimmunization according to the Rh antigens was highest in e (9.72%), c (2.48%), C (2.34%) and E (0.94%) antigens. With the ABO system, alloimmunization was highest in blood group B (10.7%), followed by A (10.6%), O (9.2%) and then AB (7.1%). Alloimmunization was more prevalent in D- (24%) than in D+ participants (8.9%). Rhesus antigen e was the most prevalent antigen (99.8%), followed by c. The alloimmunization rate of 9.8% among these participants is high, and appears in both D+ and D- women. The other Rhesus antigens are seen to cause alloimmunization, with antigen e causing the highest prevalence. In conclusion, there is a need to identify antibodies and study the outcome for clinical significance, especially in D+ women, to facilitate proper pregnancy management.

EVALUATION OF THE COST AND EFFECT OF PROPHYLACTIC GENOTYPIC MATCHING ON ALLOIMMUNIZATION AND AUTOIMMUNIZATION IN PATIENTS WITH SICKLE CELL DISEASE (SCD)

Blood transfusion is one of the mainstays of treatment for patients with SCD but despite of the beneficial effects, transfusion therapy can lead to red blood cell (RBC) alloimmunization with serious complications for the patient including life-threatening delayed hemolytic transfusion reactions and the hyperhemolysis syndrome. In addition, the presence of alloantibodies, which is often associated with the concomitant presence of autoantibodies, can lead to difficulty in finding compatible units, which can cause transfusion delays. To reduce alloimmunization some strategies have been implemented to provide antigen matched RBC transfusions to patients with SCD who need chronic transfusion support. In this context, phenotypic and genotypic matching protocols have been used. Based on this, the aim of this study was to evaluate the cost and the effect of prophylactic RBC transfusion genotypic matching on alloimmunization and autoimmunization in patients with SCD. Our study included 79 (33 male and 46 female) patients with SCD, homozygous for HbS, on chronic RBC transfusion therapy receiving prophylactic genotypic matching RBC transfusions in the last two years. In this period, patients received RBC units genotypic matched for Rh, K, Fya/Fy/b, Jka/Jkb, S/s, Doa/Dob and Dia antigens. Molecular matching was performed according to previous molecular typing results performed by the HEA BeadChip (Immucor) in patients and donors. Adsorption onto autologous RBC was also performed to aid the differentiation of autoantibodies from alloantibodies. The cost and availability of compatible units by performing genotypic matching were compared to serologic matching. The patients received a range of 5-215 units. And the median age in this group was 39 years old. Of the 79 patients, 17 (21.5%) were alloimmunized before they started receiving genotypic matched RBC transfusions. During this study-period only 2 patients (2.5%) with Rh variants developed alloantibodies (1 anti-C, 1 anti-e) and no patient produced autoantibody. Although the availability of compatible units has decreased when compared to serological matching, it was possible to find compatible units for most patients. A cost reduction of 30% was observed in the genotypic matching compared to the serological matching for the selected matched antigens. RBC transfusions with extended genotypic matching had significant effects on autoimmunization and alloimmunization rates in chronically transfused patients with SCD over two years. Alloimmunization rates have shown to decrease from a range of 21.5 to 2.5% in these patients. SCD patients may benefit from receiving prophylactic genotypic matching RBC transfusions as demonstrated by the reduction on the rates of alloimmunization, autoimmunization and cost.

ALLOIMMUNIZATION PREVALENCE IN PATIENTS WITH SICKLE CELL DISEASE (SCD): ASSESSMENT OF THREE TRANSFUSION PROTOCOLS

RBC alloimmunization is a major complication associated with RBC transfusion in patients with SCD with serious complications for the patient including life-threatening delayed hemolytic transfusion reactions and an increase in the risks inherent to transfusion such as TRALI, infectious diseases and the hyperhemolysis syndrome. In addition, the presence of alloantibodies, which is often associated with the concomitant presence of autoantibodies, can lead to difficulty in finding compatible units, which can cause transfusion delays. The prevalence of alloimmunization vary according to the transfusion protocols used and may be reduced by matching for RBC antigens. Based on this, the aim of this study was to assess the prevalence of RBC alloimmunization in patients receiving transfusions with ABO and D matching, with phenotype matching for C, E and K antigens and with extended minor RBC antigen matching. A total of 368 patients with SCD, homozygous for HbS were enrolled. In this period, 81 patients received RBC units matched for ABO and RhD, 188 patients were matched for C, E and K and 99 patients were matched for ABO, Rh, K, Fya/Fy/b, Jka/Jkb and S/s antigens. Transfusion and antibody histories were obtained from our records, and antibody screening was done to assess the alloimmunization prevalence. Molecular typing was performed in all patients who had recent transfusions or a positive direct antiglobulin test by Laboratory Developed Tests (LDT) and HEA BeadChip (Immucor) to predict their antigen profile. RH variant alleles were determined in patient's antigen-positive who developed Rh antibodies using RHD and RHCE BeadChips (Immucor). Adsorption onto autologous RBC was also performed to aid the differentiation of autoantibodies from alloantibodies. Of the 368 patients evaluated, 128 were male and 240 female. Mean age was 37.4 years (range 18-60) and they received an average of 74 RBC units. Prevalence of alloimmunization in the SCD patients with ABO/RhD matched only units (n=81) was 54%. For individuals transfused with C, E and K matched units (n=188), alloimmunization prevalence was 13% and patients transfused with extended-matching units (n=99) the prevalence of alloimmunization was 0.8%. Antibody specificities developed by the patients receiving Rh and K matched units were: Anti-e, -D, -Jk a , -Jk b , -S, -Di a , -V and by the patients receiving extended matching were anti-C, -e, -V, -VS. The variant RHCE*ceS , RHCE*ceMO , RHD*DIIIa-CE(4-7)-D and RHD*DAU3 alleles were associated with the production of Rh antibodies in these patients and 9.8% of the alloimmunized patients developed autoantibodies. RBC alloimmunization rates shown to decrease to 24 % in patients with SCD transfused with RBCs matched for C, E and K antigens and to 1.5 % to patients with extended matching. Provision of RBC transfusions with limited and extended antigen matching is essential to reduce the rates of alloimmunization and hemolytic transfusion reactions in patients with SCD.

Incidence of Red Cell Antibody Formation Following Massive Transfusion Protocol: Experience of a Single Institution.

Injured patients in hemorrhagic shock have a survival benefit with massive transfusion protocol (MTP). While there are many published studies on the transfusion management of massively bleeding patients, the risk of alloimmunization in patients that have received products during an MTP activation is relatively unknown. Therefore, we sought to determine the frequency of new antibody formation in MTP patients that received blood products from an uncrossmatched megapack. We conducted a retrospective data review of patients who underwent an MTP activation for trauma resuscitation between May 2014 and July 2020. Data were collected from patients who met the following criteria: MTP was activated, the patients received at least one unit of packed red blood cells, one unit of fresh frozen plasma, one unit of platelets, and had a repeat type and screen within 6 weeks of transfusion. These inclusion criteria resulted in 28 patients over the 6-year timeframe. Overall, the risk of alloimmunization secondary to MTP is 3.6% in our trauma patient population. The newly developed antibodies post-MTP are considered clinically significant, meaning they can cause hemolysis if exposed to donor red blood cells containing those antigens. Blood products should be given preferentially over crystalloids to acutely bleeding patients to prevent ischemic injury during an MTP activation despite the risk of alloimmunization. In our single-institution study, the alloimmunization rate in massive transfusions where patients receive uncrossmatched red blood cells is similar to those receiving crossmatched red blood cells.

Red blood cell alloimmunisation in multi-transfused patients from an haemodialysis service in Burkina Faso.

BackgroundIn Burkina Faso, red blood cell (RBC) transfusion remains the crucial anaemia treatment following chronic renal failure (CRF) as erythropoietin and its analogues are unavailable. However, blood group matching beyond the ABO and Rhesus is not common in Burkina Faso. Thus, alloimmunisation is a potential issue for transfused patients.ObjectiveOur study aimed to identify anti-erythrocyte antibodies in multi-transfused CRF patients at the Yalgado Ouedraogo Teaching Hospital, Ouagadougou, Burkina Faso.MethodsThis cross-sectional study, conducted from October 2018 to November 2019, included CRF patients who had received at least two RBC units. We screened patients for the presence of RBC antibodies using three commercial Cells panels and identified antibody specificities for positive screenings using 11 Cells panels for an indirect antiglobulin test (IAT) in a low ionic strength microcolumn gel-card system.ResultsTwo hundred and thirty-five patients (45.1% female; average age: 41.5 years) were included. The median number of blood units received per patient was 10 (interquartile range: 5–20). The overall alloimmunisation rate was 5.9% (14/235). Antibodies identified included: anti-D (1 case), anti-C (1 case), anti-D+C (4 cases), anti-CW (1 case), anti-E (1 case), anti-S (1 case) and anti-Lea (1 case). In four positive patients, the specificity of the antibodies was indeterminate. No risk factors were associated with alloimmunisation.ConclusionIn Burkina Faso, screening for RBC alloantibodies should be mandated for patients at risk. The high rate of indeterminate antibodies suggests the need to develop a local RBC antibody panel adapted to the local population.

Frequency and specificity of erythrocyte alloimmunization in patients at a reference hospital in Alagoas, Brazil

Objective: To determine the frequency and specificity of erythrocyte alloimmunization in patients treated by hemotherapy at the University Hospital Professor Alberto Antunes - UFAL, Maceió-Alagoas, in the period 2013-2018. Methods: Retrospective analysis all patient records with request for red blood cell concentrate (RBC) with a positive erythrocyte antibody test. Results: The incidence of erythrocyte alloimmunization was higher in women n=144 (80.45%) than in men n=35 (19.55%). We detected 13 antibodies, the most frequent specificities identified were anti-D (35.20%), anti-M (12.30%) and anti-E (7.82%). The combination of antibodies occurred in twenty-six cases with prevalence for combinations of antibodies of the Rh system, anti-D + anti-C (23.08%). The highest incidence of alloantibodies was observed in pregnant women. Conclusion: The population studied had high levels of alloimmunization through the Rh System, greater specificity of alloimmunization in women through anti-D and higher rate of alloimmunization among men over the age of 40. Further studies are necessary for a better understanding of red blood cell alloimmunization for population of Alagoas.

Racial differences in transfusion practices: Time to address structural racism

See article on page 1519–1526, in this issue

Effects of different sensitization events on HLA alloimmunization in renal transplant cases; a retrospective observation in 1066 cases

BackgroundPatients awaiting solid organ transplantation may develop anti-HLA antibodies after sensitization events such as transfusions, pregnancies, or previous transplantations. However, the effects of a particular sensitization event on HLA alloimmunization have not been well studied in parallel using cell-based assays and solid-phase assays. In this study, we evaluated and compare how different sensitization events affect the HLA antibody screening (HLA-Ab) and donor specific antibody (DSA) status in solid renal organ transplantation patients. MethodsHLA antibody (HLA-Ab) screening tests like complement-dependent cytotoxicity crossmatch (CDC-XM), flow cytometry crossmatch (FC-XM) and Luminex panel-reactive antibody (L-PRA) were performed in all 1066 patients (635 males and 431 females). If any of these tests turned out to be positive, a Luminex single antigen bead (L-SAB) assay was performed for DSA identification. Test positive rates and antibody strengths were analyzed according to the different sensitization events and gender. ResultsIn this study, HLA-Ab screening tests positive rates (L-PRA, FC-XM and CDC-XM) were significantly higher in patients with previous transplantation (73.91%, 100% and 56.52% p < 0.001), previous pregnancy (57.46%, 70.14% and 18.85% p < 0.001) or blood transfusion (27.33%, 35.55% and 7.33% p < 0.001) compared with patients without a sensitizing event (6.17%, 13.58% and 1.09). In this study, re-transplantation group showed significantly stronger antibody strength (DSA) than non sensitized group (class I and II MFI 11418.04, 17,837.78 vs class I and II MFI 2659, 3329; P < 0.001) and those with single sensitization events of transfusion (class I and II MFI 11418.04, 17,837.78 vs class I and II MFI 5790.26, 6004.16; P < 0.001) or pregnancy (class I & II MFI 11418, 17,837 vs class I and II MFI 8631.71, 7253.29; P < 0.001). ConclusionsPregnancy and blood transfused had high allo-immunization rate for class I HLA antigens. While re-transplantation patients had high allo-immunization rate for both the HLA classes (HLA- class I and HLA- class II). Re-transplantation group showed significantly stronger antibody strength, followed by pregnancy and then transfusion.

Occurrence of Erythrocyte Alloimmunization in Women Attending Antenatal Care Clinic

Background and Objectives: There is limited literature available on the alloimmunization rates among pregnant women in India. Our primary aim was to estimate the occurrence of irregular erythrocyte alloantibody (IEA) immunization amongst women attending our antenatal care (ANC) clinic and to guide our obstetricians for improved ANC as well as their fetal outcomes. Methods: A cross-sectional study was performed at the blood center in North India over 12 months. We recruited a total of 212 study participants. Antibody screening and identification were performed by using semi-automated column agglutination technology and commercially available 3-red cell antibody screen panel with reagent cards having anti-human globulin (AHG) (Ortho Clinical Diagnostics Inc., USA) and 11-red cell antibody identification panel with reagent cards having AHG (Resolve Panel A; Ortho Clinical Diagnostics Inc., USA) respectively. Once identified, the semi-quantitative doubling dilutions, i.e., serial titrations of the respective IEA were performed by the conventional tube technique to assess their potency. The association of various antibodies identified was analyzed using the Pearson's Chi-square test. Results: Of the 7248 pregnant women attending our ANC clinics, the antibody screening was requested for 212 cases. Out of these, 10.8% (n = 23/212) of women were positive and were sensitized both by active and passive immunization. Their average age (in years) was 27.6 ± 3.52 (20 to 34). The majority belonged to the Dehradun district of Uttarakhand. ABO system-wise, the most common type amongst the included subjects was A as recorded in 34.4%, followed by B (30.18%), O (24.12%) and AB (11.3%), respectively. Rh system-wise, nearly 47% (n=100/212) of subjects had Rh (D) negative blood group. Interestingly, amongst these 23 ANC cases with positive IAT, nearly 13% had a history of having received a blood transfusion. Conclusion: To sum up, the screening of majority of ANC in our hospital is restricted to Rh (D) negative pregnancies. Perhaps, more awareness among obstetricians regarding the universal screening of all ANC cases irrespective of their Rh (D) status is the need of the hour.

Retention of functional mitochondria in mature red blood cells from patients with sickle cell disease.

Sickle cell disease (SCD) is an inherited blood disorder characterized by sickled red blood cells (RBCs), which are more sensitive to haemolysis and can contribute to disease pathophysiology. Although treatment of SCD can include RBC transfusion, patients with SCD have high rates of alloimmunization. We hypothesized that RBCs from patients with SCD have functionally active mitochondria and can elicit a type 1 interferon response. We evaluated blood samples from more than 100 patients with SCD and found elevated frequencies of mitochondria in reticulocytes and mature RBCs, as compared to healthy blood donors. The presence of mitochondria in mature RBCs was confirmed by flow cytometry, electron microscopy, and proteomic analysis. The mitochondria in mature RBCs were metabolically competent, as determined by enzymatic activities and elevated levels of mitochondria-derived metabolites. Metabolically-active mitochondria in RBCs may increase oxidative stress, which could facilitate and/or exacerbate SCD complications. Coculture of mitochondria-positive RBCs with neutrophils induced production of type 1 interferons, which are known to increase RBC alloimmunization rates. These data demonstrate that mitochondria retained in mature RBCs are functional and can elicit immune responses, suggesting that inappropriate retention of mitochondria in RBCs may play an underappreciated role in SCD complications and be an RBC alloimmunization risk factor.

Red blood cell alloimmunization among recipients of blood transfusion in India: A systematic review and meta-analysis.

There is a varied prevalence of red cell alloimmunization being reported from different parts of India. This study aimed to estimate the overall prevalence of alloimmunization in India by performing a systematic review of the literature and to establish the most suitable antigen-matching strategy to reduce the red blood cell (RBC) alloimmunization rate among transfusion recipients. A systematic search of all the original articles published in English on RBC alloimmunization among transfusion recipients from India in MEDLINE, SCOPUS, CINAHL and Google Scholar bibliographic databases was conducted. After screening the articles as per inclusion/exclusion criteria, data extraction was done independently by two sets of investigators. Meta-analysis was performed by the binary random-effects model using the restricted maximum likelihood method. A total of 44 studies on RBC alloimmunization, with a cumulative sample size of 309,986 patients, were grouped into hospital-based and multiply-transfused patients, which yielded a prevalence of 0.5 (95% confidence interval; 0.3-0.8) and 4.8 (95% confidence interval; 3.9-5.7) per 100 patients, respectively. As many as 1992 alloantibodies were identified among the 1846 alloimmunized patients. The most common antibody identified was anti-E (127; 31.99%), followed by anti-c (75; 18.89%) in multiply-transfused patients. The rate of alloimmunization was 0.5 per 100 patients tested for antibodies and 4.8 per 100 patients receiving transfusion. Considering E- and c-antigen-matched red cells along with ABO and RhD matching may significantly reduce the overall occurrence of alloimmunization among Indian population who are transfusion-dependent.

Granulocyte Transfusions in Patients with Chronic Granulomatous Disease Undergoing Hematopoietic Cell Transplantation or Gene Therapy.

Granulocyte transfusions are sometimes used as adjunctive therapy for the treatment of infection in patients with chronic granulomatous disease (CGD). However, granulocyte transfusions can be associated with a high rate of alloimmunization, and their role in CGD patients undergoing hematopoietic cell transplantation (HCT) or gene therapy (GT) is unknown. We identified 27 patients with CGD who received granulocyte transfusions pre- (within 6 months) and/or post-HCT or GT in a retrospective survey. Twelve patients received granulocyte transfusions as a bridge to cellular therapy. Six (50%) of these patients had a complete or partial response. However, six of 10 (60%) patients for whom testing was performed developed anti-HLA antibodies, and three of the patients also had severe immune-mediated cytopenia within the first 100 days post-HCT or GT. Fifteen patients received granulocyte transfusions post-HCT only. HLA antibodies were not checked for any of these 15 patients, but there were no cases of early immune-mediated cytopenia. Out of 25 patients who underwent HCT, there were 5 (20%) cases of primary graft failure. Three of the patients with primary graft failure had received granulocyte transfusions pre-HCT and were subsequently found to have anti-HLA antibodies. In this small cohort of patients with CGD, granulocyte transfusions pre-HCT or GT were associated with high rates of alloimmunization, primary graft failure, and early severe immune-mediated cytopenia post-HCT or GT. Granulocyte transfusions post-HCT do not appear to confer an increased risk of graft failure.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10875-022-01261-1.

Red Cell Alloimmunization and Autoimmunization Among Sickle Cell Disease and Thalassemia Patients in Jazan Province, Saudi Arabia.

PurposeSickle cell disease (SCD) and thalassemia are common inherited blood disorders in Saudi Arabia, especially in Jazan Province. Patients with these disorders require multiple blood transfusions, which may lead to alloimmunization because of mismatched blood group antigens. In this study, we examined the alloimmunization and autoimmunization rates in patients with SCD and thalassemia together with the involved antibodies.Patients and MethodsA cross-sectional study was conducted to review the transfusion history records of patients with SCD and thalassemia at Prince Mohammed bin Nasser Hospital, Jazan Province, Saudi Arabia.ResultsFour-hundred thirty-eight patients (385 with SCD, 52 with β-thalassemia, and 1 with α-thalassemia) were received leukoreduced red cell transfusions. The alloimmunization and autoimmunization rates in patients with SCD were 12.98% and 0.52%, respectively. In patients with thalassemia, the alloimmunization and autoimmunization rates were 13.21% and 3.77%, respectively. The most prevalent antibodies in the study population were anti-E (17.19%) and anti-K (14.06%).ConclusionThe alloimmunization and autoimmunization rates were determined in patients with SCD and thalassemia in Jazan Province, Saudi Arabia. The results highlight the need for extended phenotyping to include ABO, RH (D, C, c, E, e), K, Fya, Fyb, Jka and Jkb antigens in the screening panel. This will benefit patients to ensure better transfusion practices.

Emergency Clinicians interpretation and application of Anti-D guidelines

Objective: The objective of this study was to audit the use of anti-D immunoglobulin (anti-D) against the current Australian guidelines in one large inner-city referral hospital over three years and critique the practice identified. Background: Pregnant patients who have a D-negative (RhD negative) blood type are at risk of D alloimmunisation if a potentially sensitising event occurs during pregnancy or birth. The administration of anti-D Ig can prevent complications related to alloimmunisation. Potentially sensitising events commonly present to the emergency department requiring the administration of anti-D Ig in line with current guidelines. Study Design and Methods: This is a retrospective cohort study of all patients who received anti-D Ig in a large inner-city emergency department (ED) over three years (July 2014 – June 2017). Indications for administration were scrutinised against current guidelines by experienced clinicians. Results: A total of 228 patients received anti-D Ig, with the majority being less than twelve weeks in gestation (169, 74.1%). Anti-D Ig was administered without support from the guidelines in 81 (35.5%) patients, with a lack of documented sensitising event in 77 (95%) of these cases. Discussion and Conclusion: There were inconsistencies amongst clinicians who prescribe anti-D Ig in the ED, and a lack of the application of current guidelines. This may stem from a lack of empirical evidence about the need for anti-D Ig in the most common group presenting to EDs, those under twelve weeks in gestation. Current guidelines also fail to take into consideration future need, which could be incorporated in future, ED specific anti-D Ig guidelines. Implications for research, policy, and practice: This audit identified overuse of anti-D Ig in the ED. This may stem from the absence of evidence for its use in pregnant patients under 12 weeks in gestation. To reduce unsupported use, further data on alloimmunisation rates following potentially sensitising events in early pregnancy would be helpful. Additional guidelines specific to patients under 12 weeks in gestation, and presenting to the emergency department may reduce some unsupported usage. What is already known about the topic? Pregnant patients who have an D-negative blood type are at risk of D alloimmunisation when a sensitising event occurs. It is common for patients to present to the emergency department with complications in early pregnancy Previous work has shown that there is variation in anti-D Ig administration in the emergency department. What this paper adds: There is significant use of anti-D Ig in the emergency department that is outside of current guidelines. The current guidelines may not serve the needs of the majority of presentations in the emergency department. Further data on alloimmunisation rates following potentially sensitising events in patients less then twelve weeks of gestation would be useful.

Anti-D Alloimmunization After RhD Positive Red Cell Transfusion to Selected RhD Negative Patients.

Transfusion of RhD positive red cells to RhD negative individuals is not routine transfusion practice for the fear of alloimmunization. Aim of this study was to prospectively evaluate rate of alloimmunization after transfusion of RhD positive red cells in RhD negative individuals and to assess delay in transfusion due to decision making. This was a prospective, observational study conducted from 2014 to 2018. All patients were followed up for a period of three months, at 3, 14, 45 and 90days with antibody screening. In addition, patients who were immunosuppressed and alloimmunized were followed up at 6months and one year. During the period of the study, there were a total of 57 RhD negative patients (52 males and five females) who received a mean of 4.42 ± 2.85 transfusions. Alloimmunization was detected in 8 (14.03%) patients at a mean interval of 25.63 ± 16.04days. Anti-D was detected in seven and one patient developed anti-E alloantibody. Mean number of red cell units transfused in alloimmunized was 1.7 ± 0.26 while it was 5.4 ± 1.82 in non-alloimmunized group. There was no delay in providing units to these patients. The TAT was found to be 68min. Rate of alloimmunization after transfusion of RhD positive red cells to RhD negative individuals was found to be 12.3%. In life saving conditions, RhD negative patients can be transfused RhD positive red cells without delay in decision making.

Antenatal antibody screening irrespective of RH status at a tertiary care hospital: A prospective study

Maternal alloimmunization is still the leading cause of fetal anemia and is responsible for neonatal mortality and morbidity in developing countries. Evidence-based guidelines are essential for implementing antenatal alloantibodies screening in developing countries like India which will help to formulate recommendations and reduce adverse outcomes of Hemolytic disease of fetus and new born. To determine the frequency of alloimmunization among in Antenatal women during routine antenatal visits irrespective of Rh status. The prospective study carried out in a tertiary care hospital has enrolled 1000 antenatal women (500 each of Rh-positive and Rh-negative women) attending antenatal clinics and admitted for institutional deliveries, were screened for red cell alloimmunization and association between alloimmunization rate in antenatal women with variables was carried out to determine the clinical significance. Among 1000 antenatal women enrolled and screened 33 (3.3%) antenatal women were found to be alloimmunized. The prevalence of alloimmunization among Rh-negative women is 5.4% (27/500). While the prevalence of alloimmunization among Rh-positive women is 1.2% (6/500). Majority of the alloimmunized cases were multigravida. 75.7% (25/33) antibodies identified in our study were anti-D antibodies and 24.24% (8/33) were non anti-D antibodies. Successful implementation of Antenatal antibody screening program requires a coordinated Team approach between the Transfusion medicine, Obstetrics, Radiology and Pediatrics departments. Early screening irrespective of Rh status and effective utilization of RhIg prophylaxis in Rh negative antenatal women is the only solution to reduce fetal, neonatal morbidity and mortality due to alloimmunization.

Red cell alloimmunization in transfusion-dependent β-thalassemia patients attending Alexandria University Children Hospital

Background In Egypt, it has been established that the most frequently inherited disorder of hemoglobin is β-thalassemia. Management of the severe forms of this disorder consists chiefly of red cell transfusion. The concerned patients receive these transfusions on a regular basis. Therefore, the formation of antired cell alloantibodies and autoantibodies was inevitable. This dilemma is addressed in this study that aims to determine the prevalence of red cell alloimmunization among transfusion-dependent ß-thalassemia children that receive frequent care in the Hematology Clinic of Alexandria University Children’s Hospital. Patients and methods This study screened 100 transfusion-dependent patients in total, all of them were 3–16 years old. Transfusion and clinical records of the latter were reviewed to assess the diagnosis of β-thalassemia, the age of the first presentation, the age at which transfusion therapy was started, transfusion interval, and the number of red cell units given. Alloantibody detection was then performed. Results In the present study, 11 (11%) out of the total 100 studied patients were alloimmunized. The total number of alloantibodies identified in these patients was 25. Two patients (18%) had only one alloantibody, six patients (54.5%) had two alloantibodies, one patient (9%) had three alloantibodies, and two patients (18%) had more than three alloantibodies. The most prevalent antibodies belonged to Kell and Rh blood-group systems (seven out of 25 each). Conclusions When it comes to thalassemia patients dependent on blood transfusion, red blood cell alloimmunization is a difficult complication. Kell and RH blood-group-system antibodies are the predominant antibodies. Formation of alloantibodies depends mainly on the nature of red cell units received and donor and recipient factors. These can explain the difference in alloimmunization rates in different reports. Avoidance of alloimmunization would decrease the cost of treatment on the long run and improve the patient quality of life.