Immunohematological evaluation of red cell alloimmunization and statistical assessment of various adsorption techniques in warm autoimmune hemolytic anemia

Adsorption techniques are widely applied to detect underlying masked alloantibodies in warm autoimmune hemolytic anemia (WAIHA). We established various adsorption techniques with an aim to detect alloimmunization in WAIHA This study conducted over a period of nine years included 298 patients of WAIHA. Complete immunohematological evaluation was performed on these 298 samples following departmental protocols. Clinical and laboratory details of patients were obtained from patient files. Various adsorption methods were performed and statistically evaluated in the study. Out of 479 cases of autoimmune hemolytic anemia, WAIHA comprised of 62.2 % (N = 298). A total of 139 (46.6 %) serum samples revealed autoantibodies. Adsorption study was performed in 101 (72.7 %) indicated samples and 24 (23.8 %) of these showed 26 alloantibodies. Among the patients subjected to adsorption study hemolytic marker were significantly deranged in the alloimmunization group (p < 0.01). Polyethylene glycol (PEG) adsorption was the quickest (52.2-54.6 min) of all adsorption techniques with minimum (1.3-1.5) numbers of adsorptions needing for complete removal of serum antibodies. The LISS-papain (LP) technique was found to be more sensitive and specific compared to the other two techniques. The agreement between PEG adsorption and LP adsorption was found to be 'perfect' (96.4 %) with a Cohen's kappa (k) value of 0.9. We conclude that identification of alloantibody specificities underlying a warm autoantibody is critical for a safe and effective transfusion. All WAIHA patients with history of blood transfusion, pregnancy or both should be subjected to adsorption study. Selection of a suitable adsorption technique depends on multiple important factors.

Frequency and Underlying Causes of Alloimmunization Against Red Blood Cell Antigens in Patients Referred to the Blood Bank of the Tertiary Referral Hospital of Tehran from 2018 to 2020

BACKGROUND

Alloimmunization against blood group antigens is an important non-infectious complication of blood transfusion, and early detection of these alloantibodies by antibody screening before transfusion is crucial. Identifying which underlying factors will affect the occurrence of alloimmunization will be necessary to manage this event as accurately as possible. We aimed to assess the prevalence rate and main determinants of RBC alloimmunization among patients referred to a large referral blood bank in Iran.

METHODS

This retrospective cross-sectional study was conducted on all patients referred to a blood bank at Imam Khomeini Hospital between October 2018 and September 2020. Information was collected by referring to the archives of the hospital information system as well as the documents recorded at the blood bank ward and reviewed by two pathologists and completed documents.

RESULTS

In total, 39270 cases were cross-matched. Accordingly, the frequency of alloimmunization cases was equal to 220 cases, which indicated a prevalence of 0.56%. The most common alloantibodies were anti-K (43.2%, 95% CI: 36.8‒49.5), anti-E (34%, 95% CI: 27.7‒40.5), and anti-C (16.3%, 95% CI: 11.4‒21.4). Among patients with positive alloimmunization, the most common blood groups were blood group B (34.6%), followed by blood group A (34.1%). Most of these patients were Rh-positive (77.3%). In patients with positive alloimmunization, the frequency of hemoglobinopathy was estimated to be 37.7%. Frequent blood transfusions were found in 42.2%, a history of malignancy in 17.3%, graft history in 11.3%, and a history of pregnancy in 35.0%.

CONCLUSION

Alloimmunization was more prevalent and more predictable among patients with hemoglobinopathies and those receiving recurrent transfusions. Therefore, a history of repeated blood transfusions should be regarded as a risk factor contributing to alloimmunization.

Alloantibody among Thalassemia patients receiving multiple blood transfusions at a tertiary care hospital in India

Regular blood transfusion is a lifesaving treatment for thalassemia patients; however, it exposes them to multiple alloantigens. The present study was designed to assess the frequency of alloantibodies in thalassemia patients receiving multiple blood transfusions. Blood samples were tested by Gel card method for ABO, Rh, Direct Antiglobulin Test (DAT), Indirect Antiglobulin Test (IAT), Auto Control (AC) and presence of alloantibody. Alloantibody screening and identification were performed using commercial 3-cell and 11-cell identification panels. Of a total of 66 thalassemia patients, 37 were male and 29 were female, with a mean age of 15.63±5.93 years and a range of 4.0 to 29.0 years. The ABO profiles of thalassemia patients were B-33, A-19, O-11, and AB-3, with 63 Rh-D positives and 3 Rh-D negatives. An average of 533.39±284.95 units were transfused an average of 304±119.65 times. Positive cases for DAT were 29(43.93%), AC was 26(39.39%) and IAT was 4(6.06%). Nine (13.636%) patients had developed alloantibodies, in which anti-K was seen in 5(27.77%), anti-Kpa in 4(22.22%), anti-C in 3(16.66%), anti-Cw in 3(16.66%), anti-D in 1(5.55%), anti-Lea in 1(5.55%), anti-Lua in 1 (5.55%). Alloantibodies were single in 4(44.44%) and multiple in 5(55.55%) patients. The rate of alloimmunization and positivity of DAT, AC, ICT, and splenectomy were significantly associated with higher age, the number of units transfused, and also the number of times of transfusion. Every new thalassemia patient needs extended blood group typing prior to the start of a blood transfusion and antigen-matched blood. For patients with alloantibodies, corresponding antigen-negative blood must be selected for cross-matching.

Transfusion support for a patient with alloanti-D and the RHD*DV.1 allele

BACKGROUND

Safe blood transfusion is significantly affected by the complex antigen polymorphism and a high proportion of autoantibodies of the Rh blood group system.

THE PATIENT AND METHODS

A male Chinese patient with primary biliary cirrhosis, esophageal and gastric rupture, and bleeding was admitted to our hospital. Blood typing identified that he had serological O and D+ blood groups. Because autoantibody was not detected using routine immediate spin (IS) and indirect antiglobulin test (IAT), he was treated by transfusing D+ red blood cells (RBCs). However, this treatment was ineffective. Thus, manual polybrene test (MPT) and low ionic salt solution indirect antiglobulin test (LISS-IAT) were performed, followed by exon sequencing of the RHD gene.

RESULTS

The patient was confirmed as a DV Type 1 individual by gene sequencing, and had 4+ RhD antigen agglutination. The anti-D in serum and elution could only be detected by MPT (2+ agglutination) and LISS-IAT methods (1+/3+ agglutination). It was presumed that attenuated alloantibody contributed to ineffective RBC transfusion, causing a transient increase in hemoglobin (HGB) before falling back to 50 g/L or even lower within four days.

CONCLUSION

Genotyping helps to support the specificity of detecting autoantibodies and alloantibodies. Combining more serological methods with molecular technology in blood typing is beneficial to improve the safety and effectiveness of blood transfusion.

Alloantigen Copy Number as a Critical Factor in RBC Alloimmunization

RBC alloimmunization remains a significant barrier to ongoing transfusion therapy leading to morbidity, and in extreme cases mortality, due to delayed or insufficient units of compatible RBCs. In addition, the monitoring and characterization of alloantibodies, often with multiple specificities in a single patient, consumes substantial health care resources. Extended phenotypic matching has mitigated, but not eliminated, RBC alloimmunization and is only logistically available for specialized populations. Thus, RBC alloimmunization remains a substantial problem. In recent decades it has become clear that mechanisms of RBC alloimmunization are distinct from other antigens and lack of mechanistic understanding likely contributes to the fact that there are no approved interventions to prevent RBC alloimmunization from transfusion. The combination of human studies and murine modeling have identified several key factors in RBC alloimmunization. In both humans and mice, immunogenicity is a function of alloantigen copy number on RBCs. Murine studies have further shown that copy number not only changes rates of immunization but the mechanisms of antibody formation. This review summarizes the current understanding of quantitative and qualitative effects of alloantigen copy number on RBC alloimmunization.

A novel method for in vitro culture and expansion of nonhuman primate B cells

BACKGROUND

Given the role of B cells in sensitization and antibody-mediated rejection pathogenesis, the ability to identify, isolate, and study B cells in vitro is critical for understanding these processes and developing novel therapeutics. While in vivo nonhuman primate models have been used to this end, an in vitro nonhuman primate model of B cell activation and proliferation has not been developed.

METHODS

CD20+ B cells and CD3+ T cells were isolated using magnetic bead separation from the peripheral blood of naive and skin allograft sensitized nonhuman primates. Allogeneic B and T cells were co-cultured in plates pre-coated with murine stromal cells engineered to express human CD40L and stimulated with cytokines. Cells and supernatants were harvested every 2 days for immune phenotyping and donor specific antibody quantification by flow cytometry.

RESULTS

The optimized culture system consisted of MS40L cells co-cultured with B and allogenic T cells and stimulated with cytokines. This culture system resulted in increased memory cells and plasmablasts over time compared to other culture systems. Comparison of culture of naïve and sensitized nonhuman primate samples revealed faster B cell exhaustion and marginally increased plasmablast differentiation in sensitized culture. Donor-specific antibody production was not observed in either culture group.

CONCLUSIONS

This study describes the first in vitro nonhuman primate model of B cell activation and proliferation using both naïve and allosensitized samples. This model provides an opportunity for exploration of B cell mechanisms and novel therapeutics and is a preliminary step in the development of an in vitro germinal center model.

De novo natural anti-M alloantibody emergence in severe Coronavirus Disease 2019

The immune response is a key player in the course of SARS-CoV-2 infection, and is often seriously dysfunctional in severe Coronavirus Disease 2019. The hyperinflammatory status has been described to be accompanied by the appearance of autoantibodies. In a lethal COVID-19 infection, we observed the emergence of a de novo natural alloantibody which targeted the M antigen from the MNS blood group on red blood cells (RBC) without evidence of any cross-reaction with SARS-CoV-2 antigens. This IgM lambda alloantibody was unmutated and unswitched. Here, we describe for the first time the emergence of a bystander de novo natural alloantibody against RBCs in a severe COVID-19 patient, highlighting the extra-follicular humoral response reported in these cases.

Immunogenetics of heteroclitic recognition of HLA-DQB1 55R eplet specificity by human alloantibody

Heteroclitic antibodies bind to a related antigen with higher affinity than to the immunizing antigen to which they were generated. This uncommon phenomenon is not well characterized for antibodies to HLA antigens. Here we analyzed allosera reactivity from two transplant recipients sensitized to mismatched donor alleles DQB1*06:01 and DQB1*06:02 respectively. Epitope analysis demonstrated the reactivity of both sera was restricted to DQB1*04, 05, and 06 alleles, with a specificity associated with the 55R eplet. Serum from one of these subjects (TE) was significantly more reactive with DQB1*04 alleles than the immunizing DQB1*06:01 or other alleles, a pattern not present in serum from the other patient. Antibody absorption/elution experiments using B cell lines expressing DQB1*06:01 or DQB1*04:02 alleles confirmed that the heteroclitic TE antibody eluted from cells carrying DQB1*06:01 was significantly more reactive with beads carrying the DQB1*04 alleles than with the DQB1*06 or other alleles. The significantly higher reactivity of the heteroclitic alloantibody with DQB1*04 specificity was explained structurally by variations of amino acid residues within 3.5 Å of 55R. These findings have important implications for the interpretation of DQ alloantibody cross-reactivity frequently observed in transplant recipients.

A rare case of a clinically significant anti-M alloantibody in a heart transplant recipient

INTRODUCTION

Anti-M antibodies are usually inactive at physiologic temperatures (37 °C). Rarely, these antibodies have been reported to react at physiologic temperatures, resulting in clinically significant hemolytic transfusion reactions or hemolytic disease of the fetus and newborn.

PATIENT AND METHODS

We describe a case of an acute hemolytic transfusion reaction due to an anti-M alloantibody reacting at physiologic temperatures in a critically ill patient.

RESULTS

Proper identification and management of anti-M antibody-mediated acute hemolysis rapidly improved and stabilized her hemoglobin.

CONCLUSION

Differentiation between anti-M antibody-mediated acute hemolysis and its differential diagnoses is of critical importance to guide therapeutic decisions in these rare clinical scenarios.

Safety assessment of RhD-positive red cell transfusion in RhD-negative liver-transplant recipients: Single-centre report from India

Background & objectives:

The number of blood components required during a liver-transplant surgery is significant. It is challenging for blood transfusion services to provide the required RhD-negative red blood cells (RBCs) for recipients during the peri-operative period. This retrospective study presents safety data of transfusing RhD-positive RBCs in RhD-negative living donor liver-transplant (LDLT) recipients during the peri-operative period with six-month follow up for risk of developing alloantibodies.

Methods:

All RhD-negative patients who underwent LDLT and were transfused ABO-compatible but RhD-positive RBC units between January 2012 and May 2018 were included in the study. Twenty one RhD-negative patients who received a total of 167 RhD-positive RBCs peri-operatively were chosen for alloantibody screening. All the patients were started on triple immunosuppression drugs as per the standard hospital protocol. Blood grouping, cross-match and antibody screening were done by column agglutination technique.

Results:

Post-transplant antibody screen (weekly for 12 wk) was negative, and none of the patients developed anti-D alloantibodies till their last follow up (mean 21 months).

Interpretation & conclusions:

Our observations suggest that it may be safe to use RhD-positive RBCs peri-operatively in RhD-negative LDLT recipients with low risk of alloimmunization.

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.

Immunohematologic aspects of alloimmunization and alloantibody detection: A focus on pregnancy and hemolytic disease of the fetus and newborn

Alloimmunization to non-ABO, red blood cell (RBC) antigens remains one of the most clinically-relevant complexities faced by blood banking practitioners. In the setting of transfusion therapy, these antibodies raise risks for incompatibilities, while for pregnant patients they can mediate deadly forms of hemolytic disease of the fetus and newborn. As such, a thorough understanding of pathways that lead to alloimmunization, as well as the tools used by blood banks to detect alloantibodies, is critical to transfusion practice. In this review, in which alloimmunization in the setting of pregnancy will be emphasized, we will review: 1) the clinical impacts of RBC alloantibodies in the peri-partum period; 2) the current pathophysiologic mechanisms thought to influence non-ABO antigen alloimmunization; 3) the strengths and weaknesses of laboratory tools used in aiding alloimmunization detection; and 4) future directions of the transfusion community related to alloimmunization impacting pregnancy.

Red cell alloantibodies in beta-thalassaemia major patients' blood referring to the regional blood transfusion center of Tehran, Iran

Introduction: Thalassemia is associated with a genetic decline in the rate of synthesis of one or more types of natural hemoglobin polypeptide chains. One of the major complications in thalassemia patients is alloimmunization, which is antibody production by the patient against transfused red blood cells (RBCs). These RBCs are unknown by the recipient and the formed antibodies against them are called alloantibodies. This study aimed to evaluate the frequency of alloantibodies against RBCs in beta-thalassemia patients referred to Tehran Regional Blood Transfusion Center.

Methods: In this study, antibody screening tests (Dia-cell I, II, and III) were performed on 184 thalassemia patients. An identification test by the Dia panel consisting of 11 different O RBCs groups to examine sera with Dia cells (I, II, or III) was performed.

Results: In our study, males and females patients comprised 66 (35.87%) and 118 (64.13%), respectively, of whom 116 (63%) had alloimmunization. In addition, 68 thalassemia subjects (37%) lacked alloantibodies. Among 184 patients with beta-thalassemia major, anti-K (Kell system), anti-D, and anti-E (Rhesus system) had the most abundant alloantibody variants with an incidence of 24 (13%), 11 (5.98%), and 10 (5.4%), respectively.

Conclusion: Before RBC transfusion, regular RBC antigen phenotypes, as well as problem-solving of alloantibody production by receiving compatible blood for Kell and RH subgroups, are suggested for all cases of transfusion-derived thalassemia.

Examining the Role of Complement in Predicting, Preventing, and Treating Hemolytic Transfusion Reactions

Red blood cell (RBC) transfusion is a critical component of optimal management for a broad range of conditions. Regardless of the indication, pretransfusion testing is required to appropriately match RBC donors and recipients to provide immunologically compatible blood. Although this approach is effective in the vast majority of situations, occasionally, patients will inadvertently receive an incompatible RBC transfusion, which can result in a hemolytic transfusion reaction (HTR). In addition, patients with life-threatening anemia and a complex alloantibody profile, which precludes rapid procurement of compatible RBCs, may also receive incompatible RBCs, placing them at risk for an HTR. Despite the rarity of these clinical situations, when incompatible blood transfusion results in an HTR, the consequences can be devastating. In this review, we will explore the challenges associated with actively preventing and treating acute HTRs following incompatible RBC transfusion. In doing so, we will focus primarily on the role of complement, not only as a key player in HTRs, but also as a potential target for the prevention and treatment of HTRs.

Assessment of Humoral Alloimmunity in Mixed Lymphocyte Reaction

Humoral alloimmunity remains a significant and unresolved problem that constrains allograft survival. Thus, there is a need for the development of an easy, preferably non-radioactive, and inexpensive protocol for assessing the effect of various drug treatments on humoral alloimmunity. In order to satisfy this demand, we developed such a protocol in which de novo alloantibodies production is induced in one-way mixed lymphocyte reaction (MLR). The amount and capacity of the generated alloantibodies in the supernatant of each one-way MLR is assessed using an antibody-mediated cell dependent cytotoxicity (CDC) assay. The principle of the assay relies on the assessment of cellular survival of resting PBMCs isolated from the same donors, supplemented with the alloantibodies from the one-way MLR supernatant. The lesser is the cellular survival, the higher the production of alloantibodies in one-way MLR and consequently the more potent the humoral alloimmunity.

Alloimmunization in Thalassemia Patients: New Insight for Healthcare

Background:

Development of alloantibodies against the foreign red blood cell (RBC) (alloimmunization) is a well-known complication in thalassemia patients when performing multiple transfusions. The study was conducted to know the prevalence of alloimmunization in thalassemia patients, in the Caspian Sea coastline.

Methods:

This study is a descriptive, retrospective analysis of transfusion records of 190 patients with β-thalassemia major who received regular transfusions. To detect the type of alloantibodies, two cells panel tests (kits; Iranian Blood Transfusion Organization [IBTO], 3 RBC cells and IBTO, 11 RBC cells) were used.

Results:

Forty-seven patients were positive for alloantibodies (24.7%). Of them, 18.4% (35 cases) had only one alloantibody, and 6.3% (12 cases) had at least two or more of alloantibodies. The vast majority of alloantibodies were anti-Kell followed by anti-E, and anti-D, respectively.

Conclusions:

Blood matching for Rh and K antigens in patients with transfusion-dependent thalassemia could reduce the rate of RBC alloinununization.

Facts and Fallacies of Kidd Antibodies: Experience in a Tertiary Care Hospital in North India

We have analyzed the method used in our laboratory to detect the most elusive, clinically significant alloantibody: the Kidd alloantibodies and find the most convenient procedure. A retrospective analysis of the method used in our laboratory for determining Kidd alloantibodies from January 2013 to May 2015 was conducted. The details of the event that sensitized the patient for red cell antibody formation and procedure used to detect the alloantibody were retrieved from the departmental records. Of 405 red cell antibody identification cases, 24 (5.9 %) had Kidd antibody (anti-Jka in 12: 50 % cases; anti-Jkb in 4: 16.7 % cases; multiple antibodies in 8: 32 % cases). Thirteen of 24 patients (54.2 %) had autocontrol positive of which 6 cases needed adsorption procedures whereas antibody/ies could be identified without adsorption procedure in the remaining 7 cases. All the 7 cases had autocontrol of 1+ strength. Of the 11 patients (45.8 %) with autocontrol negative, the antibody was identified using solid phase in 7 cases whereas tube panels were also used in the remaining 4 cases. Kidd alloantibodies though deceptive can be identified by sensitive techniques like the solid phase and simple but laborious techniques using the tube cell panels. Depending upon the reaction strength of the autocontrol, the routine autoadsorption process may be skipped and tube cell enzyme treated cells or solid phase techniques be used to get the results.

Study of alloimmunization and autoimmunization in Iranian β-thalassemia major patients

Background:

Thalassemia is one of the most common monogenic disorders characterized by reduced production of globin chains. Although regular red blood cell (RBC) transfusion support is the main treatment for these patients, it may be associated with complications such as RBC alloimmunization.

Aim:

The study aimed to determine the incidence of alloimmunization and autoimmunization to RBC antigens in β-thalassemia major patients from Zanjan, Zanjan Province, Iran.

Materials and Methods:

A total of 49 β-thalassemia major patients comprising 24 females and 25 males (mean age: 18.59 ± 8.16 years; range: 2-40 years) from Northwest Iran were included in a cross-sectional study. Alloantibody screening and identification were done using 3-cell and 10-cell reagent red blood cells, respectively. Autoantibody detection was performed using direct Coomb's test.

Results:

The incidence of alloimmunization was 16.32% with 10 alloantibodies identified in 8 patients. The most common clinically significant alloantibody identified in alloimmunized patients was anti-Kell (K-antigen) (60%) followed by anti-Rhesus (Rh) (E, c-antigens). The rate of alloimmunization was significantly lower in patients transfused with leukoreduced RBCs compared with those transfused with nonleukoreduced RBCs (9.53% vs 57.14%, P = 0.001). There was no significant correlation between alloantibody formation and the age, gender, hemoglobin levels, number of transfused units, and splenectomy.

Conclusion:

Transfusion of leukoreduced and phenotypically matched red blood cells for Kell (K) and Rh (E, c) antigens may help reduce the alloimmunization rate in Iranian β-thalassemia major patients. Moreover, autoimmunization to RBC antigens was rare in our patients.

High-throughput allogeneic antibody detection using protein microarrays

Enzyme-linked immunosorbent assays (ELISAs) have traditionally been used to detect alloantibodies in patient plasma samples post hematopoietic cell transplantation (HCT); however, protein microarrays have the potential to be multiplexed, more sensitive, and higher throughput than ELISAs. Here, we describe the development of a novel and sensitive microarray method for detection of allogeneic antibodies against minor histocompatibility antigens encoded on the Y chromosome, called HY antigens. Six microarray surfaces were tested for their ability to bind recombinant protein and peptide HY antigens. Significant allogeneic immune responses were determined in male patients with female donors by considering normal male donor responses as baseline. HY microarray results were also compared with our previous ELISA results. Our overall goal was to maximize antibody detection for both recombinant protein and peptide epitopes. For detection of HY antigens, the Epoxy (Schott) protein microarray surface was both most sensitive and reliable and has become the standard surface in our microarray platform.

Pregnancy boosts vaccine-induced Bovine Neonatal Pancytopenia-associated alloantibodies

Although maternal vaccination is generally considered to be safe, the occurrence of Bovine Neonatal Pancytopenia (BNP) in cattle shows that maternal vaccination may pose a risk to the offspring. Pregsure BVD-induced maternal alloantibodies cause BNP in newborn calves. The occurrence of BNP years after last Pregsure BVD vaccination indicates that alloantibody levels may remain high in dams. Since pregnancy induces alloantibodies we hypothesized that pregnancy boosts the vaccine-induced alloantibody response. Alloantibody levels in Pregsure BVD-vaccinated dams increased from conception towards the end of gestation and declined after parturition. In parallel, BVDV-antibody levels remained constant, indicating that there is specific boosting of alloantibodies. Since the rise in alloantibodies coincides with pregnancy and other alloantigen sources were excluded, we concluded that fetal alloantigens expressed during pregnancy boost the alloimmune response in the dam. These results help explain why BNP cases occur even years after Pregsure BVD has been taken off the market.

cPRA Increases With DQA, DPA, and DPB Unacceptable Antigens in the Canadian cPRA Calculator

A calculated panel reactive antibody (cPRA) estimates the percentage of donors with unacceptable antigens (UA) for a recipient. cPRA may be underestimated in transplant candidates with UA to DQA, DPA, and DPB if these are not included in the calculation program. To serve the National Canadian Transplant Programs, a cPRA calculator was developed with complete molecular typing for all donors at HLA-A, B, C, DRB1, DRB3/4/5, DQA1, DQB1, DPA1, and DPB1, all resolved to serologic equivalents. The prevalence of UA at DQA, DPA and DPB was evaluated in a sensitized regional population. The impact of adding these additional UA to cPRA was calculated alone and in combination, and compared to the baseline cPRA for UA at A, B, C, DR, DR51/52/53, and DQ. Of 740 sensitized transplant candidates, 18% of total and 32% with cPRA≥95% had DQA UA. Twenty-seven percent of total and 54% with cPRA≥95% had DPB UA. Of 280/740 subjects with these UA, 36/280 (13%) had cPRA increase of >20% when they were included, 7% increased cPRA to ≥80% and 6% to ≥95%. Inclusion of DQA, DPA, and DPB UA in Canadian cPRA calculations improves the accuracy of cPRA where these are relevant in allocation.

Rates and determinants of progression to graft failure in kidney allograft recipients with de novo donor-specific antibody

Understanding rates and determinants of clinical pathologic progression for recipients with de novo donor-specific antibody (dnDSA), especially subclinical dnDSA, may identify surrogate endpoints and inform clinical trial design. A consecutive cohort of 508 renal transplant recipients (n = 64 with dnDSA) was studied. Recipients (n = 388) without dnDSA or dysfunction had an eGFR decline of -0.65 mL/min/1.73 m(2) /year. In recipients with dnDSA, the rate eGFR decline was significantly increased prior to dnDSA onset (-2.89 vs. -0.65 mL/min/1.73 m(2) /year, p < 0.0001) and accelerated post-dnDSA (-3.63 vs. -2.89 mL/min/1.73 m(2) /year, p < 0.0001), suggesting that dnDSA is both a marker and contributor to ongoing alloimmunity. Time to 50% post-dnDSA graft loss was longer in recipients with subclinical versus a clinical dnDSA phenotype (8.3 vs. 3.3 years, p < 0.0001). Analysis of 1091 allograft biopsies found that dnDSA and time independently predicted chronic glomerulopathy (cg), but not interstitial fibrosis and tubular atrophy (IFTA). Early T cell-mediated rejection, nonadherence, and time were multivariate predictors of IFTA. Independent risk factors for post-dnDSA graft survival available prior to, or at the time of, dnDSA detection were delayed graft function, nonadherence, dnDSA mean fluorescence intensity sum score, tubulitis, and cg. Ultimately, dnDSA is part of a continuum of mixed alloimmune-mediated injury, which requires solutions targeting T and B cells.

An Anti-C1s Monoclonal, TNT003, Inhibits Complement Activation Induced by Antibodies Against HLA

Antibody-mediated rejection (AMR) of solid organ transplants (SOT) is characterized by damage triggered by donor-specific antibodies (DSA) binding donor Class I and II HLA (HLA-I and HLA-II) expressed on endothelial cells. While F(ab')2 portions of DSA cause cellular activation and proliferation, Fc regions activate the classical complement cascade, resulting in complement deposition and leukocyte recruitment, both hallmark features of AMR. We characterized the ability of an anti-C1s monoclonal antibody, TNT003, to inhibit HLA antibody (HLA-Ab)-induced complement activation. Complement deposition induced by HLA-Ab was evaluated using novel cell- and bead-based assays. Human aortic endothelial cells (HAEC) were cultured with HLA-Ab and human complement; production of activated complement proteins was measured by flow cytometry. Additionally, C3d deposition was measured on single antigen beads (SAB) mixed with HLA-Ab and human complement. TNT003 inhibited HLA-Ab mediated complement deposition on HAEC in a concentration-dependent manner; C3a, C4a and C5a anaphylatoxin production was also diminished by TNT003. Finally, TNT003 blocked C3d deposition induced by Class I (HLAI-Ab)- and Class II (HLAII-Ab)-specific antibodies on SAB. These data suggest TNT003 may be useful for modulating the effects of DSA, as TNT003 inhibits complement deposition and split product formation generated by HLA-I/II-Ab in vitro.

Haematopoietic depletion in vaccine-induced neonatal pancytopenia depends on both the titre and specificity of alloantibody and levels of MHC I expression

Bovine Neonatal Pancytopenia (BNP) is a disease of calves characterised by haematopoietic depletion, mediated by ingestion of alloantibodies in colostrum. It has been linked epidemiologically to vaccination of the dams of affected calves with a particular vaccine (Pregsure) containing a novel adjuvant. Evidence suggests that BNP-alloantibodies are directed against MHC I molecules, induced by contaminant bovine cellular material from Madin-Darby Bovine Kidney (MDBK) cells used in the vaccine's production. We aimed to investigate the specificity of BNP-alloantibody for bovine MHC I alleles, particularly those expressed by MDBK cells, and whether depletion of particular cell types is due to differential MHC I expression levels. A complement-mediated cytotoxicity assay was used to assess functional serum alloantibody titres in BNP-dams, Pregsure-vaccinated dams with healthy calves, cows vaccinated with an alternative product and unvaccinated controls. Alloantibody specificity was investigated using transfected mouse lines expressing the individual MHC I alleles identified from MDBK cells and MHC I-defined bovine leukocyte lines. All BNP-dams and 50% of Pregsure-vaccinated cows were shown to have MDBK-MHC I specific alloantibodies, which cross-reacted to varying degrees with other MHC I genotypes. MHC I expression levels on different blood cell types, assessed by flow cytometry, were found to correlate with levels of alloantibody-mediated damage in vitro and in vivo. Alloantibody-killed bone marrow cells were shown to express higher levels of MHC I than undamaged cells. The results provide evidence that MHC I-specific alloantibodies play a dominant role in the pathogenesis of BNP. Haematopoietic depletion was shown to be dependent on the titre and specificity of alloantibody produced by individual cows and the density of surface MHC I expression by different cell types. Collectively, the results support the hypothesis that MHC I molecules originating from MDBK cells used in vaccine production, coupled with a powerful adjuvant, are responsible for the generation of pathogenic alloantibodies.

Monocyte recruitment by HLA IgG-activated endothelium: the relationship between IgG subclass and FcγRIIa polymorphisms

It is currently unclear which donor specific HLA antibodies confer the highest risk of antibody-mediated rejection (AMR) and allograft loss. In this study, we hypothesized that two distinct features (HLA IgG subclass and Fcγ receptor [FcγR] polymorphisms) which vary from patient to patient, influence the process of monocyte trafficking to and macrophage accumulation in the allograft during AMR in an interrelated fashion. Here, we investigated the contribution of human IgG subclass and FcγR polymorphisms in monocyte recruitment in vitro by primary human aortic endothelium activated with chimeric anti-HLA I human IgG1 and IgG2. Both subclasses triggered monocyte adhesion to endothelial cells, via a two-step process. First, HLA I crosslinking by antibodies stimulated upregulation of P-selectin on endothelium irrespective of IgG subclass. P-selectin-induced monocyte adhesion was enhanced by secondary interactions of IgG with FcγRs, which was highly dependent upon subclass. IgG1 was more potent than IgG2 through differential engagement of FcγRs. Monocytes homozygous for FcγRIIa-H131 adhered more readily to HLA antibody-activated endothelium compared with FcγRIIa-R131 homozygous. Finally, direct modification of HLA I antibodies with immunomodulatory enzymes EndoS and IdeS dampened recruitment by eliminating antibody-FcγR binding, an approach that may have clinical utility in reducing AMR and other forms of antibody-induced inflammation.

Positive crossmatch kidney transplant recipients treated with eculizumab: outcomes beyond 1 year

This study examined outcomes beyond 1 year in eculizumab-treated (EC) positive crossmatch kidney transplants (+XMKTx) compared to a historical control group. +XMKTx received desensitization with either plasma exchange (PE) alone (N = 48) or PE and EC (N = 30). EC, given for at least 1 month, was continued in the setting of persistently high DSA (B flow cytometric crossmatch [BFXM] >200) including: 4 weeks (n = 14); 9 weeks (n = 6), 6 months (n = 2), and 12 months (n = 8). All patients had at least 2 years follow-up. The incidence of acute clinical ABMR was lower in the EC group than controls (6.7% vs. 43.8% p < 0.01). Death-censored allograft survival was similar between groups. Chronic ABMR was the main cause of graft loss. On 1-year protocol biopsies, no differences were noted between EC and controls including: cg score >0, 26.7% versus 31.9% (p = 0.62), ptc score ≥ 2, 60.0% versus 60.0% (p = 1.00), or C4d + , 33.8% versus 13.5% (p = 0.08). A persistently high BFXM in EC-treated patients was associated with cg score >0 at 1 year, while EC appeared to protect against cg if the BFXM remained low. We conclude that despite decreasing acute clinical ABMR rates, EC treatment does not prevent chronic ABMR in recipients with persistently high BFXM after +XMKTx.

Should HLA mismatch acceptability for sensitized transplant candidates be determined at the high-resolution rather than the antigen level?

Defining HLA mismatch acceptability of organ transplant donors for sensitized recipients has traditionally been based on serologically defined HLA antigens. Now, however, it is well accepted that HLA antibodies specifically recognize a wide range of epitopes present on HLA antigens and that molecularly defined high resolution alleles corresponding to the same low resolution antigen can possess different epitope repertoires. Hence, determination of HLA compatibility at the allele level represents a more accurate approach to identify suitable donors for sensitized patients. This approach would offer opportunities for increased transplant rates and improved long term graft survivals.

Circulating NK-cell subsets in renal allograft recipients with anti-HLA donor-specific antibodies

Detection of posttransplant donor-specific anti-HLA antibodies (DSA) constitutes a risk factor for kidney allograft loss. Together with complement activation, NK-cell antibody-dependent cell mediated cytotoxicity (ADCC) has been proposed to contribute to the microvascular damage associated to humoral rejection. In the present observational exploratory study, we have tried to find a relationship of circulating donor-specific and non donor-specific anti-HLA antibodies (DSA and HLA non-DSA) with peripheral blood NK-cell subsets and clinical features in 393 renal allograft recipients. Multivariate analysis indicated that retransplantation and pretransplant sensitization were associated with detection of posttransplant DSA. Recipient female gender, DR mismatch and acute rejection were significantly associated with posttransplant DSA compared to HLA non-DSA. In contrast with patients without detectable anti-HLA antibodies, DSA and HLA non-DSA patients displayed lower proportions of NK-cells, associated with increased CD56(bright) and NKG2A(+) subsets, the latter being more marked in DSA cases. These differences appeared unrelated to retransplantation, previous acute rejection or immunosuppressive therapy. Although preliminary and observational in nature, our results suggest that the assessment of the NK-cell immunophenotype may contribute to define signatures of alloreactive humoral responses in renal allograft recipients.

What's hot, what's new at WTC--basic science

The World Transplant Congress of 2014 presented a broad swath of science that touched on many disparate aspects of cell and organ transplantation, molecular and cellular immunology, systems biology, development, technology and translation into humans. A number of themes emerged this year. B cell biology and antibody chemistry were prominent, as they have been for several years. T cells, co-stimulatory blockade and regulatory T cells continue to dominate many aspects of immune research. Many new aspects of monocyte, macrophage, NK cell and NK T cell development, biology and regulation are now being explored. Diverse aspects of organ injury and the acute and chronic responses to injury are being investigated with new techniques, new targets and a resurgent vigor. Novel advances in xenotransplantation and experimental tolerance garnered much attention. Newer investigations in microbiota and nanotechnology promise significant gains in the near future. Lastly the 'omics of DNA, RNA, proteins, metabolites, bacteria and enzyme actions promise new understanding in biological systems and how to control those systems.

B cell activating factor (BAFF) and a proliferation inducing ligand (APRIL) mediate CD40-independent help by memory CD4 T cells

Donor-reactive memory T cells undermine organ transplant survival and are poorly controlled by immunosuppression or costimulatory blockade. Memory CD4 T cells provide CD40-independent help for the generation of donor-reactive effector CD8 T cells and alloantibodies (alloAbs) that rapidly mediate allograft rejection. The goal of this study was to investigate the role of B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) in alloresponses driven by memory CD4 T cells. The short-term neutralization of BAFF alone or BAFF plus APRIL synergized with anti-CD154 mAb to prolong heart allograft survival in recipients containing donor-reactive memory CD4 T cells. The prolongation was associated with reduction in antidonor alloAb responses and with inhibited reactivation and helper functions of memory CD4 T cells. Additional depletion of CD8 T cells did not enhance the prolonged allograft survival suggesting that donor-reactive alloAbs mediate late graft rejection in these recipients. This is the first report that targeting the BAFF cytokine network inhibits both humoral and cellular immune responses induced by memory CD4 T cells. Our results suggest that reagents neutralizing BAFF and APRIL may be used to enhance the efficacy of CD40/CD154 costimulatory blockade and improve allograft survival in T cell-sensitized recipients.

[Anti-erythrocyte and anti-HLA immunization in hemoglobinopathies]

AIM

Evaluate the anti-erythrocyte and anti-HLA immunization rates in hemoglobinopathies.

PATIENTS AND METHODS

Cross-sectional study (October 2009-March 2010) on 83 patients followed for hemoglobinopathies. The irregular antibodies research is realized by two techniques: indirect Coombs and enzymatic technique on gel cards. The search for anti-HLA class I antibodies is done by complement dependent lymphocytotoxicity.

RESULTS

The mean age was 30 years (14-64 years), the sex ratio M/F is 0.84. Our series included 42 cases of sickle cell disease (29 homozygous sickle cell anemia and 13 sickle-thalassemia) and 41 cases of thalassemia syndromes (26 major and 15 intermediate). The anti-erythrocyte alloimmunization rate is 10.84% without difference between thalassemia syndromes and sickle cell disease. The autoimmunization rate (22.89%) is higher in thalassemia syndromes (41.46%) than in the sickle cell disease (7.14%) (P<0.001). The anti-HLA immunization rate is 31.6% without difference between thalassemia syndromes and sickle cell disease. The young age, transfusion at a young age and the total number of transfusions are the factors that increase the risk of anti-erythrocyte autoimmunization. No clinicobiological parameter does influence the anti-erythrocyte and anti-HLA alloimmunization. There is no significant association between anti-erythrocyte and anti-HLA immunization.

CONCLUSION

The erythrocyte and anti-HLA anti-immunization rates are high in our series. Preventive strategy is needed to ensure optimal blood safety.

The clinical spectrum of de novo donor-specific antibodies in pediatric renal transplant recipients

The development of donor-specific HLA antibodies (DSA) is associated with worse renal allograft survival in adult patients. This study assessed the natural history of de novo DSA, and its impact on renal function in pediatric renal transplant recipients (RTR). HLA antibodies were measured prospectively using single-antigen-bead assays at 1, 3, 6 and 12 months posttransplant followed by 12-monthly intervals and during episodes of allograft dysfunction. Of 215 patients with HLA antibody monitoring, 75 (35%) developed DSA at median of 0.25 years posttransplant with a high prevalence of Class II (70%) and HLA-DQ (45%) DSA. DSA resolved in 35 (47%) patients and was associated with earlier detection (median, inter-quartile range 0.14, 0.09-0.33 vs. 0.84, 0.15-2.37 years) and lower mean fluorescence intensity (MFI) (2658, 1573-3819 vs. 7820, 5166-11 990). Overall, DSA positive patients had more rapid GFR decline with a 50% reduction in GFR at mean 5.3 (CI: 4.7-5.8) years versus 6.1 (5.7-6.4) years in DSA negative patients (p = 0.02). GFR decreased by a magnitude of 1 mL/min/1.73 m(2) per log10 increase in Class II DSA MFI (p < 0.01). Using Cox regression, independent factors predicting poorer renal allograft outcome were older age at transplant (hazard ratio 1.1, CI: 1.0-1.2 per year), tubulitis (1.5, 1.3-1.8) and microvasculature injury (2.9, 1.4-5.7). In conclusion, pediatric RTR with de novo DSA and microvasculature injury were at risk of allograft failure.

Successful transplantation of kidney allografts in sensitized rats after syngeneic hematopoietic stem cell transplantation and fludarabine

Current methods to remove donor-specific HLA antibody (DSA) from sensitized patients remain imperfect. We tested novel approaches to desensitization using an animal model of allogeneic sensitization with skin grafts from dark agouti (DA) to Lewis rats. At the peak IgG alloantibody response we transplanted DA kidneys into nephrectomized Lewis recipients (n = 6) and all died within 10 days from antibody-mediated rejection (AMR). Allogeneic hematopoietic stem cell transplants (HSCT) from DA donors failed to engraft after lethal or sub-lethal irradiation. Sensitized rats given lethal irradiation plus syngeneic green fluorescent protein (GFP) + HSCT had repopulation of blood, spleen, thymus and lymph nodes by GFP+ cells. At 2 months after HSCT, serum DSA levels were reduced 60-70% and DSA (IgG) production in cultured splenocytes was also significantly decreased. However, there was only a modest improvement in graft survival from an average of 6.5 to 13.9 (n = 9) days. Adding seven daily doses of fludarabine to the preconditioning regimen resulted in long-term survival (>90 days) in 7 out of 10 rat kidney allografts. We conclude that syngeneic HSCT performed after preconditioning with irradiation and fludarabine can reduce DSA, prevent DSA rebound and AMR, enabling successful transplantation in animals with strong antibody reactivity to the donor MHC.

HLA antibody detection with solid phase assays: great expectations or expectations too great?

Alloantibodies directed against HLA antigens, are a barrier to long-term solid organ allograft survival. The clinical impact of preformed, donor-directed HLA alloantibodies range from acceptable risk to unequivocal contraindication for organ transplantation. HLA antibodies are key factors that limit patient access to donor organs. Serological methods were once the only approach to identify HLA antigens and antibodies. Limitations in these technologies led to the development of solid phase approaches. In the early 1990s, the development of the polymerase chain reaction enabled DNA-based HLA antigen testing to be performed. By the mid-1990s, microparticle-based technology that utilized flow cytometry for analysis was developed to detect both classes I and II HLA antibodies. These methodologies revolutionized clinical histocompatibility testing. The strengths and weaknesses of these assays are described in detail in this review.

Incompatible blood transfusion: Challenging yet lifesaving in the management of acute severe autoimmune hemolytic anemia

Background and Aim:

Autoimmune hemolytic anemia (AIHA) is characterized by the production of autoantibodies directed against red cell antigens. Most patients of AIHA arrive in the emergency or out-patient department (OPD) with severe anemia requiring urgent blood transfusion. Here we share our experience of managing these patients with incompatible blood transfusions and suggest the minimal test required to assure patient safety.

Materials and Methods:

A total of 14 patients admitted with severe anemia, diagnosed with AIHA and requiring blood transfusion urgently were included in the study. A series of immunohematological investigations were performed to confirm the diagnosis and issue best match packed red blood cells (PRBC) to these patients.

Results:

A total of 167 PRBC units were crossmatched for 14 patients of which 46 units (28%) were found to be best match ones and 26 (56.5%) of these units were transfused. A mean turn around time of 222 min was observed in issuing the “best match” blood. Severe hemolysis was observed in all patients with a median hemoglobin increment of 0.88 g/dl after each unit PRBC transfusion.

Conclusion:

Decision to transfuse in AIHA should be based on the clinical condition of the patient. No critical patient should be denied blood transfusion due to serological incompatibility. Minimum investigations such as direct antiglobulin test (DAT), antibody screening and autocontrol should be performed to ensure transfusion safety in patients. All transfusion services should be capable of issuing “best match” PRBCs in AIHA.

RBC alloimmunization and double alloantibodies in thalassemic patients

PURPOSE

Alloimmunization is a common consequence of chronic blood transfusion. Double alloantibody production may complicate the condition of such patients especially for finding matched blood. In this study, we evaluated the frequency of alloantibodies in thalassemic patients with previous history of transfusion reactions.

SAMPLES AND METHODS

This study was performed on 441 multiply transfused thalassemia patients Antibody screening test was carried out using three cell-panel by gel method. Positive patients were followed up for antibody identification using 11-cell panel. Direct combs' test was performed to detect auto antibodies.

RESULTS

In a total of 441 cases (362 thalassemia major and 79 intermedia), 234 were males (53.1%) and 207 females (46.9%); mean age 22 years, range 3-61 years. Alloimmunization was detected in 50(11.3%) patients, including 37(74%) patients with one alloantibody, 8(16%) with two antibodies, 4(8%) patients with unknown antibodies and one patient (2%) with autoantibody. The most common alloantibodies were anti-Rh antibodies (-E/e/C/c/Cw) (26%), anti-K (28%), anti-D (16%), and anti-Colton (4%). Double antibodies were detected in eight out of 50 patients, including: Anti-D+anti-C (8%), anti-D+anti-E (2%), anti-Kell+anti-D (2%), and anti-Kell+KPa (2%). A significant association was observed between the transfusion reaction history and the alloantibody detection results (p < 0.05).

CONCLUSION

Antibody production against RBC antigens makes hard condition in regular blood transfusion. Double antibodies production may more complicate this situation. Thus, it is advisable to phenotype patients and matches the red cells in multiply transfused thalassemia patients.

Quantifying the risk of incompatible kidney transplantation: a multicenter study

Incompatible live donor kidney transplantation (ILDKT) offers a survival advantage over dialysis to patients with anti-HLA donor-specific antibody (DSA). Program-specific reports (PSRs) fail to account for ILDKT, placing this practice at regulatory risk. We collected DSA data, categorized as positive Luminex, negative flow crossmatch (PLNF) (n = 185), positive flow, negative cytotoxic crossmatch (PFNC) (n = 536) or positive cytotoxic crossmatch (PCC) (n = 304), from 22 centers. We tested associations between DSA, graft loss and mortality after adjusting for PSR model factors, using 9669 compatible patients as a comparison. PLNF patients had similar graft loss; however, PFNC (adjusted hazard ratio [aHR] = 1.64, 95% confidence interval [CI]: 1.15-2.23, p = 0.007) and PCC (aHR = 5.01, 95% CI: 3.71-6.77, p < 0.001) were associated with increased graft loss in the first year. PLNF patients had similar mortality; however, PFNC (aHR = 2.04; 95% CI: 1.28-3.26; p = 0.003) and PCC (aHR = 4.59; 95% CI: 2.98-7.07; p < 0.001) were associated with increased mortality. We simulated Centers for Medicare & Medicaid Services flagging to examine ILDKT's effect on the risk of being flagged. Compared to equal-quality centers performing no ILDKT, centers performing 5%, 10% or 20% PFNC had a 1.19-, 1.33- and 1.73-fold higher odds of being flagged. Centers performing 5%, 10% or 20% PCC had a 2.22-, 4.09- and 10.72-fold higher odds. Failure to account for ILDKT's increased risk places centers providing this life-saving treatment in jeopardy of regulatory intervention.

Prevalence of irregular red blood cell antibodies among healthy blood donors in Delhi population

OBJECTIVES

To evaluate the prevalence of the anti-red blood cell antibodies among healthy blood donors.

MATERIAL AND METHODS

Antibody screening of all voluntary blood donor serum was performed as routine immunohematological procedure. Positive sera were further investigated to identify the specificity of irregular erythrocyte antibody by commercially available red cell panel (ID-Dia Panel, Diamed-ID Microtyping System).

RESULT

A total of 47,450 donors were screened for the presence of irregular erythrocyte antibodies. A total of forty-six donors showed presence of alloantibodies in their serum (46/47,450%, 0.09%), yielding a prevalence of 0.09%. Most frequent alloantibodies identified were of MNS blood group system. The results showed statistically a higher prevalence of RBC alloantibodies in females than in males.

CONCLUSION

Screening for presence of alloantibodies in donor blood is important to provide compatible blood products and to avoid transfusion reactions.

Alloimmunization to Red Cells and the Association of Alloantibodies Formation with Splenectomy Among Transfusion-Dependent β-Thalassemia Major/HbE Patients

Severe hemolytic anemia in β-thalassemia major and β-thalassemias/HbE (β-TM) patients requires giving blood transfusions. Chronic blood transfusions lead to iron overload consequence with organs damage and risk of alloantibody-formation. This study evaluates the prevalence of red cell alloimmunization and estimates the risk of alloantibody-formation in chronic transfusion-dependent β-TM patients. This cross sectional study was conducted on 143 β-TM patients receiving regular transfusions. We tried to determine the frequency, types and factors influencing red cell alloimmunization in these transfusion-dependent β-TM patients. Median age of 25 (17.5 %) alloantibody-formation β-TM patients was 19.0 years (inter quartile 15.5-24.0 years). The alloantibodies were Anti-Rh (E) (13.1 %), Anti-Rh (D) (0.7 %). Thirty-four patients (23.8 %) of the sample had splenectomies of which 10 (29.4 %) had alloantibody-formation. The interval from first transfusion to antibody development varied from 1.5 to 14 years. Alloantibody-formation correlated with splenectomy and splenectomy correlated with number of transfusion (p < 0.005). In multiple logistic regression used to estimate the risk of alloantibodies formation with splenectomy; OR and 95 % CI were 2.88 (1.07-7.80), p = 0.037 after adjusting for other co-variates. The rate of red cell alloimmunization was 17.5 % and splenectomy associated with increased alloantibody-formation in these transfusion-dependent β-TM patients.

A centralized recipient database enhances the serologic safety of RBC transfusions for patients with sickle cell disease

OBJECTIVES

To evaluate the utility of a centralized transfusion service model in preventing the transfusion of incompatible units in patients with sickle cell disease (SCD).

METHODS

The serologic records of transfused patients with SCD were reviewed. The index hospital was where an alloantibody was initially detected.

RESULTS

In total, 150 patients with SCD were evaluated; 66 (44.0%) of 150 were alloimmunized. In 42 (63.6%) of these patients, 1 or more antibodies evanesced. The median number of hospitals visited by patients with SCD for RBC transfusion with 1 or more evanesced antibodies was three (range, one to eight); the median number of nonindex hospitals was two (range, one to seven). Of the patients with evanesced antibodies, 28.6% received transfusions at various nonindex hospitals 20 or more times after the antibody evanesced.

CONCLUSIONS

A centralized database can help identify patients with SCD who have evanesced alloantibodies and prevent issuing incompatible RBC units.

Alloprimed CD8(+) T cells regulate alloantibody and eliminate alloprimed B cells through perforin- and FasL-dependent mechanisms

While it is well known that CD4(+) T cells and B cells collaborate for antibody production, our group previously reported that CD8(+) T cells down-regulate alloantibody responses following transplantation. However, the exact mechanism involved in CD8(+) T cell-mediated down-regulation of alloantibody remains unclear. We also reported that alloantibody production is enhanced when either perforin or FasL is deficient in transplant recipients. Here, we report that CD8(+) T cell-deficient transplant recipient mice (high alloantibody producers) exhibit an increased number of primed B cells compared to WT transplant recipients. Furthermore, CD8(+) T cells require FasL, perforin and allospecificity to down-regulate posttransplant alloantibody production. In vivo CD8-mediated clearance of alloprimed B cells was also FasL- and perforin-dependent. In vitro data demonstrated that recipient CD8(+) T cells directly induce apoptosis of alloprimed IgG1(+) B cells in co-culture in an allospecific and MHC class I-dependent fashion. Altogether these data are consistent with the interpretation that CD8(+) T cells down-regulate posttransplant alloantibody production by FasL- and perforin-dependent direct elimination of alloprimed IgG1(+) B cells.

CD40-independent help by memory CD4 T cells induces pathogenic alloantibody but does not lead to long-lasting humoral immunity

CD40/CD154 interactions are essential for productive antibody responses to T-dependent antigens. Memory CD4 T cells express accelerated helper functions and are less dependent on costimulation when compared with naïve T cells. Here, we report that donor-reactive memory CD4 T cells can deliver help to CD40-deficient B cells and induce high titers of IgG alloantibodies that contribute to heart allograft rejection in CD40-/- heart recipients. While cognate interactions between memory helper T and B cells are crucial for CD40-independent help, this process is not accompanied by germinal center formation and occurs despite inducible costimulatory blockade. Consistent with the extrafollicular nature of T/B cell interactions, CD40-independent help fails to maintain stable levels of serum alloantibody and induce differentiation of long-lived plasma cells and memory B cells. In summary, our data suggest that while CD40-independent help by memory CD4 T cells is sufficient to induce high levels of pathogenic alloantibody, it does not sustain long-lasting anti-donor humoral immunity and B cell memory responses. This information may guide the future use of CD40/CD154 targeting therapies in transplant recipients containing donor-reactive memory T cells.

Delayed hemolytic transfusion reaction with multiple alloantibody (Anti S, N, K) and a monospecific autoanti-JK(b) in intermediate β-thalassemia patient in Tabriz

It appears that delayed hemolytic transfusion reactions may occur several days after the administration of donor red cells is true even though they have been shown to be compatible in cross match tests by the antiglobulin technique. A specific case was observed in our center, which confirms the fact. The patient was a 37-year-old male suffering from intermediate β-thalassemia. He had a history of two previous transfusions, with unknown transfusion reaction. In the last transfusion, laboratory data showed: Hb 7.8 g/dL and Hematocrit (Hct) 24.2%. The patient received two units of cross matched, compatible concentrated red blood cells (RBCs). After eight days a severe reaction was observed with clinical evidence of tachycardia, fatigue, fever, back pain, chest discomfort, jaundice, nausea and anorexia. Accordingly delayed hemolytic transfusion reaction was suspected, and anti-RBC antibodies were tested. Laboratory tests revealed the presence of three alloantibodies: Anti-N, anti-S, anti-K, and a monospecific autoanti-JK(b).

Use of bortezomib to treat anti-HLA antibodies in renal transplant patients: a single-center experience

Donor-specific human leukocyte antigen (HLA) antibodies (DSA) are associated with decreased graft survival and may cause graft rejection. Bortezomib, a selective inhibitor of the 26S proteasome developed to treat multiple myeloma, has been used for its anti-plasma cell activity in patients undergoing transplantation. We describe our experience with bortezomib used to reduce anti-HLA antibodies in eight renal transplant patients. Patients received bortezomib (1.3mg/m(2)) on days 1, 4, 8, and 11 beginning when antibodies were detected. It was used alone in one patient and was complemented with plasmapheresis in five patients, with IVIG in one patient, and with IVIG and plasmapheresis in another patient. De novo DSA class II were detected in all eight patients and two also had DSA class I. Antibodies were entirely eliminated in five (62.5%) patients 90 days after treatment but only reduced in the other three (62.5%). Notably, they later increased in one patient. Five (62.5%) patients had AMR, two (25%) had mixed rejection, and one had no rejection. our results suggest that bortezomib is effective for reducing DSA avoiding chronic graft injury.

Alloimmunization among transfusion-dependent thalassemia patients

BACKGROUND

Thalassemia is a common hemoglobin disorder in Iran and one of the major public health problems. Although blood transfusions are lifesavers for thalassemia patients, they may be associated with some complications especially erythrocyte alloimmunization. The purpose of this study was to investigate the prevalence of red blood cell alloantibodies and to determine types of these antibodies among multiple-transfused thalassemic patients.

MATERIALS AND METHODS

A total of 313 thalassemia patients in the northeast of Iran, who received regular blood transfusion, were included in this study. Screening of antibodies was performed on fresh serum of all patients and then antibodies were identified in patients' serum that had positive antibody screening test using a panel of recognized blood group antigens.

RESULTS

We identified 12 alloantibodies in 9 patients (2.87%) that all were against Rhesus (Rh) blood group antigens (D, C, E). Three patients developed 2 antibodies, and others had one antibody. The most common alloantibodies were Anti-D (88.88%) and followed by Anti-C and Anti-E. Higher frequency of alloimmunization was observed in female, Rh negative and splenectomized patients.

CONCLUSION

This study showed that evaluation of the packed cells for Rh (C, E) from the start of transfusion can be helpful in decreasing the rate of alloantibody synthesis.