Current approaches for risk assessment of intestinal transplant patients: A view from the histocompatibility laboratory.

Despite its recent decline in volumes, intestinal transplantation remains an important option for patients with irreversible intestinal failures. The long-term outcome of an intestinal transplant has stagnated. The major cause of graft loss is rejection, resulting from mismatches in human leukocyte antigens (HLA) and the presence of antibodies to mismatched donor-specific HLA antigens (DSA). Literature has reported that DSAs, either preformed before transplantation or developed de novo after transplantation, are harmful to intestinal grafts, especially for those without combined liver grafts. A comprehensive assessment of DSA by the histocompatibility laboratory is critical for successful intestinal transplantation and its long-term survival. This paper briefly reviews the history and current status of different methods for detecting DSA and their clinical applications in intestinal transplantation. The focus is on applying different antibody assays to manage immunologically challenging intestinal transplant patients before and after transplantation. A clinical case is presented to illustrate the complexity of HLA tests and the necessity of multiple assays. The review of risk assessment by the histocompatibility laboratory also highlights the need for close interaction between the laboratory and the intestinal transplant program.

Assessment of Rapid Optimized 96-well Tray Flow Cytometric Crossmatch (Halifax-FCXM) with Luminex Single Antigen Test.

INTRODUCTION: Flow cytometric crossmatch assay (FCXM) is a sensitive cell-based method for evaluating the presence of donor-specific antibodies (DSA) before transplantation. Recently, 96-well tray FCXM protocol (Halifax FCXM) with improved test efficiency has been introduced. The objective of the present study was to assess the performance of Halifax FCXM by correlating with DSA results based on single antigen bead (SAB) assays (virtual crossmatch, VXM). METHODS: A total of 341 FCXMs were evaluated for the detection of HLA-DSA. A positive VXM was defined as having at least one HLA - DSA (HLA-A, B, Cw, DR, DQB1) with ≥ 1000 MFI (mean fluorescence intensity) identified by SAB assay. RESULTS: Of a total 341 cases, 113 showed class I VXM (+) with class I DSA MFI ≥ 1000 exclusively against one or more donor HLA class I antigens (HLA-A, B, Cw), 72 had class I-/II + DSA, and 156 had VXM(-). Halifax T-FCXM showed a sensitivity of 87.6% (99/113) and a specificity of 98.2% (224/228) for detecting class I VXM (+). The concordance between T-FCXM and class I VXM was 94.7% (323/341). Halifax B-FCXM showed a sensitivity of 58.3% (42/72) and a specificity of 98.7% (154/156) for detecting class I-/II + DSAs. The concordance between B-FCXM and class I-/II + VXM was 86.0% (196/228). When we separately analyzed data, B-FCXM detected HLA-DR (+) (68.8%) and HLA-DQ (+) DSAs (71.0%) similarly (P > 0.05). T-FCXM detected 87.6%, 97.2%, and 98.2% of class I DSA-positive cases with MFI values (sumDSA) ≥ 1000, ≥ 3000, and ≥ 5000, respectively. B-FCXM detected 58.3% of class I-II + DSA -positive (≥1000) cases, but detected 76.7% (33/43) and 89.2% (33/37) of class I-II + DSAs if MFI values of sumDSA and immunodominant DSA (iDSA) were above 5000, respectively. Halifax FCXM had sensitivities of 91.5% and 96.2% for detecting VXM (+) having MFI values above 5000 for class I or class II sumDSA and iDSA, respectively. CONCLUSION: Halifax FCXM showed a good correlation, especially with SAB assay-based high MFI DSA or sumDSA. Concurrent application of FCXM with VXM can improve pre-transplant risk assessment and progress organ allocation efficiency.

Racial/ethnic disparities among women receiving intrauterine transfusions for alloimmunization at a single fetal treatment center.

Disparities are prevalent in numerous areas of healthcare. We sought to investigate whether there were racial/ethnic disparities among pregnant women with the most severe form of alloimmunization who require intrauterine transfusions (IUT). We reviewed patients who underwent IUT for alloimmunization at a single fetal treatment center between 2015 and 2020. This "IUT cohort" was compared to an "Alloimmunization cohort": patients seen at our institution with a diagnosis of alloimmunization during pregnancy, who did not receive IUT. We collected maternal demographics including self-identified race/ethnicity and primary language, transfusion, and antibody characteristics. The cohorts were compared using unpaired t-tests, Mann-Whitney tests, and Fischer's exact tests, as appropriate. The IUT cohort included 43 patients and the alloimmunization cohort included 1049 patients. Compared to the alloimmunization cohort, there were significantly more patients of Latina descent in the IUT cohort (23.3% vs. 3.4%, p < .0001), and more non-English speakers (18.6% vs. 4.6%, p = .001). Twenty-one percent (9/43) of patients had immigrated to the United States, all of whom had pregnancies or miscarriages in their country of origin. A third of patients had new antibodies identified on serial screens during the current pregnancy. Significantly more women of Latina ethnicity and non-English speakers required IUTs compared to the cohort of women with alloimmunization. Insufficient access to care prior to arriving in the United States and among racial and ethnic minorities in the United States may contribute to these findings. Providers should be cognizant of potential, racial, and ethnic inequalities among women receiving intrauterine transfusions.

Center-level Variation in HLA-incompatible Living Donor Kidney Transplantation Outcomes.

BACKGROUND: Desensitization protocols for HLA-incompatible living donor kidney transplantation (ILDKT) vary across centers. The impact of these, as well as other practice variations, on ILDKT outcomes remains unknown. METHODS: We sought to quantify center-level variation in mortality and graft loss following ILDKT using a 25-center cohort of 1358 ILDKT recipients with linkage to Scientific Registry of Transplant Recipients for accurate outcome ascertainment. We used multilevel Cox regression with shared frailty to determine the variation in post-ILDKT outcomes attributable to between-center differences and to identify any center-level characteristics associated with improved post-ILDKT outcomes. RESULTS: After adjusting for patient-level characteristics, only 6 centers (24%) had lower mortality and 1 (4%) had higher mortality than average. Similarly, only 5 centers (20%) had higher graft loss and 2 had lower graft loss than average. Only 4.7% of the differences in mortality (P < 0.01) and 4.4% of the differences in graft loss (P < 0.01) were attributable to between-center variation. These translated to a median hazard ratio of 1.36 for mortality and 1.34 of graft loss for similar candidates at different centers. Post-ILDKT outcomes were not associated with the following center-level characteristics: ILDKT volume and transplanting a higher proportion of highly sensitized, prior transplant, preemptive, or minority candidates. CONCLUSIONS: Unlike most aspects of transplantation in which center-level variation and volume impact outcomes, we did not find substantial evidence for this in ILDKT. Our findings support the continued practice of ILDKT across these diverse centers.

Fetal and Neonatal Alloimmune Thrombocytopenia-New Prospects for Fetal Risk Assessment of HPA-1a-Negative Pregnant Women.

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare and potentially serious bleeding condition in the fetus/newborn. FNAIT is usually considered as the platelet counterpart of hemolytic disease of the fetus and newborn. In FNAIT, maternal alloantibodies against paternally inherited platelet antigens traverse the placenta and cause thrombocytopenia in the fetus/newborn. The most common and most serious cases of FNAIT among white people are caused by alloantibodies against the human platelet antigen 1a (HPA-1a), which is absent in 2.3% of women. Today, there is no screening for FNAIT, and for this reason, FNAIT is not suspected until an otherwise healthy child, born at term, presents with thrombocytopenia. Clinical management of subsequent pregnancies at risk of FNAIT is mostly based on the obstetric history. During the last 5 decades, hemolytic disease of the fetus and newborn caused by antibodies against RhD has successfully been prevented by administration of hyperimmune anti-D IgG drug products to RhD-negative women after delivery of an RhD-positive child. Similarly, a hyperimmune anti-HPA-1a IgG (NAITgam) is under development for the prevention of HPA-1a immunization and FNAIT. If NAITgam becomes licensed for FNAIT prophylaxis and national health authorities decide to include FNAIT screening in their antenatal health care programs, it will be necessary to improve today's tools for assessing the risk of FNAIT. Although the primary risk factor for HPA-1a immunization is platelet type HPA-1bb, not all HPA-1a-negative women develop anti-HPA-1a. The women who are HLA-DRB3:01:01 negative (72%) only rarely develop anti-HPA-1a, and for those few who become HPA-1a immunized, it is quite rare to have a child with severe thrombocytopenia. Determination of fetal HPA-1 type is important because 15% of HPA-1a-negative women will carry an HPA-1a-negative fetus and therefore not be at risk of FNAIT. The severity of FNAIT seems to be associated with the level of anti-HPA-1a. Hence, in Norway, for example, an Ab threshold of 3 IU/mL is used to distinguish between low- and high-risk pregnancies. The current review will discuss to what extent these analyses, as well as determination of subtypes of anti-HPA-1a (anti-ß3, anti-αIIbß3, and anti-αvß3) and Fc core fucosylation of anti-HPA-1a IgG, can be used as risk stratification tools.

Validation and cross-reactivity pattern assessment of monoclonal antibodies used for the screening of donor-specific IgG antibody subclasses in transplant recipients.

The screening for IgG subclass donor-specific antibodies (DSAs) in allograft recipients uses IgG1-4 subclass-specific monoclonal antibodies (mAbs) that should be mono-specific. The cross-reactivity discrepancies reported for IgG subclass-specific mAbs warranted a critical cross-reactivity pattern analysis of the IgG subclass-specific mAbs most commonly used to detect DSAs. We tested the reactivity of 2 anti-IgG1-, 3 anti-IgG2-, 1 anti-IgG3-, and 2 anti-IgG4-specific PE-conjugated mAbs against microbeads coated with IgG1-4 proteins separately. Each IgG subclass protein was coated at three densities on the beads (0.5, 1, and 2 µg of protein per 106 beads), and the PE-conjugated mAbs were titrated from 0.04 µg/mL to 5 µg/mL. The IgG subclass reactivity of the sample was acquired on the Luminex multiplex platform. Among the IgG subclass-specific mAbs, only the anti-IgG3 (clone: HP6050) mAb was mono-specific. All other mAbs tested were binding to IgG subclass proteins other than their respective immunogen, thereby being cross-reactive. IgG subclass cross-reactivity patterns were dependent on the concentration of both IgG subclass-specific mAbs and IgG1-4 protein targets coated onto the beads. With the current IgG subclass mAbs available, 3 of the 15 possible combinations of IgG1-4 subclass protein could be identified. While the remaining 12 unique combinations cannot be distinguished clearly, 6 groups that corresponded to two different unique combinations of IgG1-4 subclass protein could be identified. The dilution of serum samples and IgG subclass-specific mAbs, other than the anti-IgG3 (clone: HP6050), must be further optimized before their implementation in IgG subclass DSA screening in allograft recipients.

Luminex screening first vs. direct single antigen bead assays: Different strategies for HLA antibody monitoring after kidney transplantation.

MAIN PROBLEM: Luminex panel and single antigen beads (SAB) are used for screening and DSA specificity determination respectively. The cost of SAB may limit its general use, so some labs perform SAB tests only after positive screening. METHODS: We compared both strategies: 1) SAB only if positive screening with kits from manufacturer A, and 2) direct SAB from manufacturer B, and correlate their sensitivity with histological findings. RESULTS: We selected 118 kidney transplant recipients with a normal biopsy (n = 19), histological antibody-mediated damage (ABMR, n = 52) or interstitial fibrosis/tubular atrophy (IFTA, n = 47) following Banff 2015 and 2017 classification. Direct SAB detected DSA in 13 patients missed by screening. Strategy 1 detected DSA in 0% normal, 61.5% ABMR and 8.5% IFTA patients; percentages with strategy 2 were 5.2%, 78.8% and 14.8% (p=0.004). Strategy 2 identified DSA allowing full ABMR diagnosis in 17% cases missed by strategy 1. Thereafter, direct SAB from manufacturer A confirmed DSA in 46% DSA-positive cases with strategy 2 (55.5% ABMR cases). CONCLUSIONS: Luminex screening failed to identify clinically relevant HLA antibodies, hampering DSA detection in patients with possible ABMR. Direct SAB testing should be the chosen strategy for post-transplantation monitoring, albeit direct SAB from the two existing manufacturers may diverge in as much as 50% of cases.

Prophylaxis therapy with bypassing agents in patients with haemophilia A and inhibitors undergoing surgery: A cost analysis in Spain.

OBJECTIVES: This study estimated the cost of prophylaxis with activated prothrombin complex concentrate (aPCC) and recombinant activated factor VIIa (rFVIIa) in surgical patients with haemophilia A and inhibitors in Spain. METHODS: A decision-analytic model was developed to estimate the cost to the Spanish National Health System of providing haemostatic coverage in this haemophilia population, with age distribution and average weight derived from the literature, and the annual number of surgeries (0.33 per patient) from local data. Drug costs were calculated from official ex-factory prices with a 7.5% mandatory deduction and recommended dosing regimens. RESULTS: The estimated average costs per patient were €10 100.73 (aPCC) and €14 265.89 (rFVIIa) for dental extraction, €24 043.88 (aPCC) and €62 301.08 (rFVIIa) for minor surgery and €126 595.81 (aPCC) and €347 731.09 (rFVIIa) for major surgery. Assuming an estimated 23 annual surgeries in this population (N = 69), distributed as 19% dental extraction, 50% minor surgery and 31% major surgery, the total annual cost of prophylaxis was €1 209 682.35 with aPCC and €3 221 929.28 with rFVIIa. CONCLUSIONS: aPCC costs were 62.5% lower than rFVIIa. Assuming potential clinical equivalence, aPCC is a potentially cost-saving option for surgical patients with haemophilia A and inhibitors.

Fast and low-cost direct ELISA for high-throughput serological HPA-1a typing.

BACKGROUND: Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is caused by maternal alloantibodies against fetal human platelet antigens (HPAs), mostly caused by anti-HPA-1a. Population-based screening for FNAIT is still a topic of debate. Logistically and financially, the major challenge for implementation is the typing of pregnant women to recognize the 2% HPA-1a-negative women. Therefore, there is need for a high-throughput and low-cost HPA-1a-typing assay. STUDY DESIGN AND METHODS: A sandwich ELISA was developed, using a monoclonal anti-GPIIIa as coating antibody and horseradish-peroxidase-conjugated recombinant anti-HPA-1a, as detecting antibody. The ELISA results were compared to an allelic discrimination PCR-assay. In phase I, samples from unselected consecutive pregnant women were tested with both assays. Phase II was part of a prospective screening study in pregnancy and genotyping was restricted to samples with an arbitrary set, OD < 0.500. RESULTS: The ELISA was optimized to require no additional handling (swirling or spinning) of stored tubes. During phase I, 506 samples were tested. In phase II, another 62,171 consecutive samples were phenotyped, with supportive genotyping in 1,902. In total 1,585 HPA-1a negative and 823 HPA-1a positive women were genotyped. The assay reached 100% sensitivity with a cut-off OD from 0.160, corresponding with a 99.9% specificity and a false-HPA-1a negative rate of 0.03. CONCLUSION: A high-throughput, low-cost, and reliable HPA-1a phenotyping assay was developed which can be used in population-based screening to select samples for testing of presence of anti-HPA-1a. Because plasma from tubes of 3- to 6-days-old samples can be used, this assay is applicable to settings with suboptimal conditions.

A novel approach reveals that HLA class 1 single antigen bead-signatures provide a means of high-accuracy pre-transplant risk assessment of acute cellular rejection in renal transplantation.

BACKGROUND: Acute cellular rejection (ACR) is associated with complications after kidney transplantation, such as graft dysfunction and graft loss. Early risk assessment is therefore critical for the improvement of transplantation outcomes. In this work, we retrospectively analyzed a pre-transplant HLA antigen bead assay data set that was acquired by the e:KID consortium as part of a systems medicine approach. RESULTS: The data set included single antigen bead (SAB) reactivity profiles of 52 low-risk graft recipients (negative complement dependent cytotoxicity crossmatch, PRA < 30%) who showed detectable pre-transplant anti-HLA 1 antibodies. To assess whether the reactivity profiles provide a means for ACR risk assessment, we established a novel approach which differs from standard approaches in two aspects: the use of quantitative continuous data and the use of a multiparameter classification method. Remarkably, it achieved significant prediction of the 38 graft recipients who experienced ACR with a balanced accuracy of 82.7% (sensitivity = 76.5%, specificity = 88.9%). CONCLUSIONS: The resultant classifier achieved one of the highest prediction accuracies in the literature for pre-transplant risk assessment of ACR. Importantly, it can facilitate risk assessment in non-sensitized patients who lack donor-specific antibodies. As the classifier is based on continuous data and includes weak signals, our results emphasize that not only strong but also weak binding interactions of antibodies and HLA 1 antigens contain predictive information. TRIAL REGISTRATION: ClinicalTrials.gov NCT00724022 . Retrospectively registered July 2008.

Meeting report of the STAR-Sensitization in Transplantation Assessment of Risk: Naïve Abdominal Transplant Organ subgroup focus on kidney transplantation.

The development of de novo donor-specific HLA antibody (dnDSA) is a critical feature contributing to late allograft failure. The complexity of the issue is further complicated by organ-specific differences, detection techniques, reliance of tissue histopathology and changing diagnostic criteria, ineffective therapies, and lack of consensus. To tackle these issues, the Sensitization in Transplantation Assessment of Risk (STAR) 2017 was initiated as a collaboration of the American Society of Transplantation and American Society of Histocompatibility and Immunogenetics consisting of 8 working groups with the goal to provide guidelines on how to assess risk and risk stratify patients based on their potential alloimmune and DSA status. Herein is a summary of discussions by the Naïve Abdominal Working Group, highlighting currently available data and identifying gaps in our knowledge on the development and impact of dnDSA following kidney transplantation.

The socioeconomic burden of patients affected by hemophilia with inhibitors.

Hemophilia is associated with a high financial burden on individuals, healthcare systems, and society. The development of inhibitors significantly increases the socioeconomic burden of the diseases. This study aimed to review and describe the burden of hemophilia with inhibitors, providing a reference scenario to assess the impact of new products in the real word. Two systematic literature reviews were performed to collect data on (i) health economics and (ii) health-related quality of life evidences in hemophilic patients with inhibitors. The costs associated with patients with hemophilia and inhibitors are more than 3 times greater than the costs incurred in those without inhibitors, with an annual cost per patient that can be higher than €1 000 000. The costs of bypassing agents account for the large majority of the total healthcare direct costs for hemophilia treatment. The quality of life is more compromised in patients with hemophilia and inhibitors compared to those without inhibitors, in particular the physical domains, whereas mental domains were comparable to that of the general population. The development of an inhibitor has a high impact on costs and quality of life. New treatments have the potential to change positively the management and socioeconomic burden of hemophilia with inhibitors.

Four-Way Kidney Exchange Transplant With Desensitization Increases Access to Living-Donor Kidney Transplant: First Report From India.

OBJECTIVES: This study reports our experience of the first 4-way kidney exchange transplant combined with desensitization in India, which allows increased access to living-donor kidney transplant for sensitized patients. MATERIALS AND METHODS: Four-way kidney exchange transplant procedures were approved by the ethics committee of our institution and the Organ Transplantation Authorization Committee of state governments of India (as per the Transplantation of Human Organs Act of India). The protocols conformed to Declaration of Istanbul principles and the ethical guidelines of the 1975 Helsinki Declaration. Written informed consent was obtained from patients, donors, and their guardians. RESULTS: In April 2016, our transplant team completed simultaneous 4-way kidney exchange transplant procedures without any medical (rejection and infections) or surgical complications. Reasons for being included for kidney exchange transplant were ABO incom-patible (2 recipients) and sensitization (2 recipients). All 4 recipients had stable graft function with no proteinuria and donor-specific antibody at 11-month follow-up on standard triple immunosup-pression. Patient and graft survival rates were both 100%. CONCLUSIONS: To the best of our knowledge, this is the first single-center report of 4-way kidney exchange transplant combined with desensitization from India. This procedure has the potential to expand living-donor kidney transplant in disadvantaged groups (eg, sensitized patients). Recipients who are hard to match due to high panel reactive antibody and difficult to desensitize due to strong donor-specific antibodies can receive a transplant with a combination of kidney exchange and desensitization. Our study suggests that 4-way kidney exchange transplant can be performed in developing countries (India) similar to that shown in programs in developed countries with team work, kidney exchange registry, and counseling.

[Is the research of posttransfusional alloantibodies still relevant?] / Est-ce que la réalisation de la recherche d'anticorps antiérythrocytaires post­transfusionnelle est toujours pertinente ?

The decision of November 6th, 2006 defining the principles of best practices recommends that posttransfusional red cell alloantibodies research is performed after one to three months after. In the University hospital of Brest, the haemovigilance unit takes charge of sending the medical prescription within the required time and centralizing the results. We wished to estimate if the realization of this research still remains relevant. METHODS: A prospective analysis was performed in 2015. We evaluated the realization rate, the red cell alloantibodies rate and the recipient adverse reactions with the diagnostic category: alloimmunization (delayed serological transfusion reaction, DSTR). RESULTS: In 2015, 2162 prescriptions were sent to the 3271 transfused patients. One thousand and eighteen red cell alloantibodies research were done, i.e. a return rate of 61%. Among them, 12 alloantibodies appeared (0.9%) within an average of 56 days. Thirty-three other alloantibodies appeared and were discovered most frequently before a new transfusion. In 10 cases, a posttransfusional research was done that was negative. A survey was conducted among GHCOH members to describe the practices in these health institutions. Twelve questionnaires were analysed. Ten institutions performed a posttransfusional alloantibodies research by issuing a prescription at the patient's exit with a return rate between 0.14 and 16%; 1 institution has a centralized organization with a return rate of 68.3%; 1566 red cell alloantibodies research were performed and among them, 24 alloantibodies appeared (1.53%). CONCLUSION: These results indicate that to be effective, the management of this biological test must be centralized. Despite this, the red cell alloantibodies rate remains very low (0.9 and 1.53%) and raises the question of the relevance of this systematic testing after transfusion, which is in any case mandatory before a new transfusion of red blood cells.

Racial differences in the development of de-novo donor-specific antibodies and treated antibody-mediated rejection after heart transplantation.

BACKGROUND: Despite improvements in outcomes after heart transplantation, black recipients have worse survival compared with non-black recipients. The source of such disparate outcomes remains largely unknown. We hypothesize that a propensity to generate de-novo donor-specific antibodies (dnDSA) and subsequent antibody-mediated rejection (AMR) may account for racial differences in sub-optimal outcomes after heart transplant. In this study we aimed to determine the role of dnDSA and AMR in racial disparities in post-transplant outcomes. METHODS: This study was a single-center, retrospective analysis of 137 heart transplant recipients (81% male, 48% black) discharged from Emory University Hospital. Patients were classified as black vs non-black for the purpose of our analysis. Kaplan-Meier and Cox regression analyses were used to evaluate the association between race and selected outcomes. The primary outcome was the development of dnDSA. Secondary outcomes included treated AMR and a composite of all-cause graft dysfunction or death. RESULTS: After 3.7 years of follow-up, 39 (28.5%) patients developed dnDSA and 19 (13.8%) were treated for AMR. In multivariable models, black race was associated with a higher risk of developing dnDSA (hazard ratio [HR] 3.65, 95% confidence interval [CI] 1.54 to 8.65, p = 0.003) and a higher risk of treated AMR (HR 4.86, 95% CI 1.26 to 18.72, p = 0.021) compared with non-black race. Black race was also associated with a higher risk of all-cause graft dysfunction or death in univariate analyses (HR 2.10, 95% CI 1.02 to 4.30, p = 0.044). However, in a multivariable model incorporating dnDSA, black race was no longer a significant risk factor. Only dnDSA development was significantly associated with all-cause graft dysfunction or death (HR 4.85, 95% CI 1.89 to 12.44, p = 0.001). CONCLUSION: Black transplant recipients are at higher risk for the development of dnDSA and treated AMR, which may account for racial disparities in outcomes after heart transplantation.

Assessment of HNA alloimmunisation risk in Northeastern Thais, Burmese and Karen.

OBJECTIVES: This study aimed to determine human neutrophil antigen (HNA) frequency, estimate possible HNA incompatibilities and predict the risk of HNA alloimmunisation in the Northeastern Thai, Burmese and Karen populations. BACKGROUND: Alloantibodies against HNA are implicated in a number of clinical conditions, including immune-mediated neutropenia and transfusion reactions. METHODS: A total of 400 unrelated healthy Thais, 261 Burmese and 249 Karen was included in this study. DNA samples were typed for HNA-1, -3, -4 and -5 systems using polymerase chain reactions with sequence-specific primers (PCR-SSP). RESULTS: In this cohort, HNA-1a was more prevalent than HNA-1b. Accordingly, the possible risk of HNA-1a alloimmunisation against HNA-1a is lower than HNA-1b (0·0802-0·1351 vs 0·2293-0·2497). This is in contrast to the situation reported in Caucasian and African populations. The predicted risk of HNA-3 incompatibility in Thais, Burmese and Karen were 28·09%, 30·66% and 22·77%, respectively. The possible risks of HNA-3a alloimmunisation were 0·0493 in Thais, 0·0608 in Burmese and 0·0196 in Karen, respectively. No individuals were found to be homozygous for HNA-4bb. The probability of developing alloantibodies against HNA-4a was low in these populations and every population in Asia. In contrast, the overall frequency of HNA-5bb homozygous individuals was high in this study, peaking at 0·192. CONCLUSIONS: This is the first study that reported the allele frequencies of HNA-1, -3, -4, and -5 in a large sample of healthy unrelated individuals from ethnic Thais, Burmese and Karen. Our results indicated the high possible risk of HNA-1, -3 and -5 alloimmunisation in these populations.

Assessment of Factor XIII.

Blood coagulation factor XIII (FXIII) is essential for maintaining hemostasis. The absence of FXIII results in severe bleeding diathesis, which without prophylaxis frequently leads to fatal bleeding. As the usual hemostasis screening tests remain normal, the diagnosis of FXIII deficiency needs specific tests. Here, we describe FXIII activity determination by the ammonia release assay, which is the first-line test in the diagnostic algorithm for FXIII deficiency. The method for another activity test, the undeservedly rarely used fibrin cross-linking assay, is also presented. Further tests used for the classification of FXIII deficiencies, measurement of FXIII activity in platelets, ELISAs for the measurement of complex plasma FXIII (FXIII-A2B2) antigen and for FXIII-A2 in plasma and platelets are also included. Detailed description of the methods for the detection and measurement of neutralizing auto- and alloantibodies is also provided.

Management of delayed hemolytic transfusion reaction in sickle cell disease: Prevention, diagnosis, treatment.

Transfusion remains a key treatment of sickle cell disease complications. However, delayed hemolytic transfusion reaction, the most serious complication of transfusion, may be life-threatening if hyperhemolysis develops. This syndrome is generally underdiagnosed because its biological and clinical features resemble those of vaso-occlusive crisis, and red blood cell antibodies are frequently absent. Further transfusions may aggravate the symptoms, leading to severe multiple organ failure and death. It is therefore essential to prevent, diagnose and treat this syndrome efficiently. Prevention is based principally on the attenuation of allo-immunization through the provision of extended-matched RBCs or the use of rituximab. However, such treatment may be insufficient. Early diagnosis might make it possible to implement specific treatments in some cases, thereby avoiding the need for secondary transfusion. Diagnosis is dependent on the knowledge of the medical staff. Finally, many treatments, including steroids, immunoglobulins, erythropoietin and eculizumab, have been used to improve outcome. Improvements in our knowledge of the specific features of DHTR in SCD should facilitate management of this syndrome.