Red Blood Cell Antigens Research Articles

Assessment of antibody responses to Newcastle disease vaccination in Nigerian indigenous chicken lines selected for sheep red blood cell antigen

This research was carried out to evaluate serum haemagglutination inhibition antibody titres to a Newcastle disease virus vaccine in two Nigerian indigenous chicken lines selected for sheep red blood cell antigens. One hundred Nigerian indigenous chickens were used. These chickens belonged to the fourth generation of flock that had been divergently distinguished into a high antibody titre chicken line (HATC) and a low antibody titre chicken line (LATC). Chicks were given a NDV vaccine at six weeks of age, while blood samples were collected from each chick at seven days post-administration. The antibody titres of chicks were determined through a haemagglutination inhibition test and the data collected were subjected to analysis of variance using SAS 9.2 version. It was found that sex had no significant effect on the antibody titre values (p>0.05), while the genetic line and sex by genetic line interaction had significant effects on the antibody titre values. Female chicks of LATC recorded a significantly lower ND antibody titre (4.21 ± 0.47) compared to HATC females (8.04 ± 2.02). Also, male chicks of LATC recorded a significantly lower ND antibody titre (4.26 ± 1.20) compared to HATC males (7.25 ± 0.48). Meanwhile, there was no significant difference between male and female chicks of LATC as well as between male and female chicks of HATC. Based on the differences observed in ND antibody titres between the genetic lines, emphasis should be placed on policies to develop HATC and LATC along ND resistance. Therefore, we recommend that when considering ND infection which exerts substantial losses to the poultry industry, HATC should be favoured over LATC.

Assessment of antibody responses to Newcastle disease vaccination in Nigerian indigenous chicken lines selected for sheep red blood cell antigen

This research was carried out to evaluate serum haemagglutination inhibition antibody titres to a Newcastle disease virus vaccine in two Nigerian indigenous chicken lines selected for sheep red blood cell antigens. One hundred Nigerian indigenous chickens were used. These chickens belonged to the fourth generation of flock that had been divergently distinguished into a high antibody titre chicken line (HATC) and a low antibody titre chicken line (LATC). Chicks were given a NDV vaccine at six weeks of age, while blood samples were collected from each chick at seven days post-administration. The antibody titres of chicks were determined through a haemagglutination inhibition test and the data collected were subjected to analysis of variance using SAS 9.2 version. It was found that sex had no significant effect on the antibody titre values (p>0.05), while the genetic line and sex by genetic line interaction had significant effects on the antibody titre values. Female chicks of LATC recorded a significantly lower ND antibody titre (4.21+0.47) compared to HATC females (8.04+2.02). Also, male chicks of LATC recorded a significantly lower ND antibody titre (4.26+1.20) compared to HATC males (7.25+0.48). Meanwhile, there was no significant difference between male and female chicks of LATC as well as between male and female chicks of HATC. Based on the differences observed in ND antibody titres between the genetic lines, emphasis should be placed on policies to develop HATC and LATC along ND resistance. Therefore, we recommend that when considering ND infection which exerts substantial losses to the poultry industry, HATC should be favoured over LATC.

How do I incorporate red cell genotyping to improve chronic transfusion therapy?

Children with transfusion dependent anemia, such as sickle cell disease (SCD) and thalassemia, are at an increased risk for developing red blood cell (RBC) alloantibodies due to their lifelong need for transfusion therapy. With the advent of genotyping, extended RBC antigen typing can be incorporated into chronic transfusion therapy programs (CTTPs) to improve patient care and provide antigen matched blood for this population of patients. The hospital, blood center (BC), and hematology clinic caring for children requiring long-term transfusion support developed a CTTP. Genotyping was performed at entry to determine patient RBC antigen type. Limited versus extended antigen matching of transfusions was provided based on known RBC antibodies. Fifty patients with the following disorders were enrolled: 20 with SCD, 23 with thalassemia, and 7 with other disorders. At enrollment, nine (18%) had RBC alloantibodies, including six (30%) of patients with SCD and three (13%) with thalassemia. Two children developed antibodies after enrollment; one warm autoantibody following limited "CEK" matched RBCs and one patient with a hemizygous variant RHD allele developed anti-D. Six (30%) patients with SCD had variant RHCE alleles; two had homozygous variant alleles and four had a variant present along with a wild type allele. We demonstrate how a CTTP can be developed in a community hospital through collaboration with the blood supplier, hospital, and clinical care team. A model of incorporating RBC genotyping informs risk for alloimmunization and allows consideration of transfusion strategy for providing prophylactic antigen matched blood.

CD47 Regulates Red Blood Cell Alloimmunization in Mice

Background: Exposure to red blood cell (RBC) alloantigens during pregnancy or transfusion can lead to the development of alloantibodies and result in transfusion-related complications, including hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. However, the factors that regulate RBC alloimmunization remain incompletely understood. Several studies suggest that alterations in factors that regulate RBC clearance may impact RBC uptake and antigen presentation, directly influencing the likelihood of RBC alloimmunization. To test this, we directly examined the potential role of CD47, a master regulator of RBC removal previously shown to be altered during RBC senescence and cold storage. To accomplish this, we crossed transgenic mice that express the model HOD antigen (a fusion protein consisting of hen egg lysozyme fused to ovalbumin and human Duffy b) with CD47 knock out (KO) mice to generate HOD RBC donors with wild type, heterozygous or homozygous KO levels of CD47 and used these donors to define the impact of CD47 on antibody formation following RBC transfusion. Methods: HOD transgenic mice expressing the HOD antigen exclusively on RBCs were crossed with CD47-/- mice to produce HOD CD47+/- or HOD CD47-/- mice. HOD and CD47 levels were assessed by flow cytometric analysis using anti-HOD and anti-CD47 antibodies. HOD CD47+/+, HOD CD47+/- or HOD CD47-/- RBCs were transfused into C57BL6 recipients, followed by serum collection on days 14 and 28 post transfusion and evaluation of anti-HOD antibodies by flow cytometry crossmatch. To determine the CD4 T cell response to transfusion, TCR transgenics specific to ovalbumin (OTII) were labeled with CFSE, followed by adoptive transfer, transfusion of HOD CD47+/+, HOD CD47+/- or HOD CD47-/- RBCs and evaluation of T cell proliferation, activation and cytokine secretion. Cellular removal of HOD RBCs was determined by flow cytometric examination of CFSE-labeled HOD RBCs. Finally, antigen levels on HOD RBCs was determined by staining cells with anti-HEL antibodies followed by flow cytometric examination. All three groups were subjected to one-way ANOVA analysis with a p value <0.05 considered significant. Results: While HOD CD47+/+ RBCs expressed levels of CD47 comparable to WT RBCs, HOD CD47+/- RBCs exhibited significantly reduced CD47 levels (nearly half that observed on WT HOD RBCs) and HOD CD47-/-RBCs failed to express any detectable CD47 (p < 0.0001). Following transfusion, HOD CD47+/- and HOD CD47-/- RBCs produced significantly higher levels of IgG anti-HOD antibodies than HOD CD47+/+ RBCs on days 14 and 28 post-transfusion (p < 0.001). However, while HOD CD47-/- RBCs displayed increased clearance consistent with the possible enhancement of a CD4 T cell response (p < 0.0001), HOD CD47+/- RBCs failed to exhibit any different in clearance when compared to HOD CD47+/+ RBCs overtime. To examine the potential impact of differences in HOD RBC clearance on CD4 T cell activation, OTII T cell proliferation was evaluated. While HOD CD47-/- RBC transfusion resulted in significantly increased 33D1+ dendritic cell uptake, OTII proliferation, activation and cytokine secretion (p < 0.05), no difference in 33D1+ dendritic cell uptake or T cell response was observed following HOD CD47+/+ RBC or HOD CD47+/- RBC transfusion. Instead, HOD CD47+/- RBCs exhibited enhanced antigen removal, while also displaying an increased ability to activate HEL specific B cells when compared to HOD CD47+/+ or HOD CD47-/- RBC transfusion. Conclusions: These results demonstrate that alterations in CD47, which occur during normal RBC senescence and cold storage, directly influence RBC alloimmunization through different mechanisms depending on the extent of CD47 loss. While complete loss of CD47 results in enhanced RBC clearance, antigen presentation and CD4 T cell activation, reductions in CD47 to half WT levels failed to impact RBC clearance or T cell activation, but instead enhanced antigen specific B cell activation. These results demonstrate that even partial loss of CD47 is capable of significantly enhancing alloantibody formation completely independent of its role in regulating RBC clearance. In doing so, these findings provide novel insight into the role of CD47 as a key regulator of RBC alloimmunization. Disclosures Stowell: Grifols: Honoraria.

Prospective evaluation of immune haemolysis in liver transplantation.

Immune haemolysis in liver transplant (LT) can occur due to autoantibodies and alloantibodies. The aim of this study was to evaluate the prevalence and risk factors for immune haemolysis in LT. A total of 175 consecutive patients were included. Multiorgan recipients were excluded. Samples, from before LT, seven consecutive days and weekly for 4weeks, were evaluated for haemolysis and immunohaematological tests. SPSS 24 was used for statistical analysis. Nine patients (5·1%) presented positive antibody screen (AS) before LT, (2·3% clinically significant), more frequent in RhD-negative (P=0·017). Positive DAT occurred in 53 (30·3%) and was related to high MELD score (P=0·048), HCV (P=0·005) and furosemide use (P=0·001). Positive AS after LT occurred in 22 patients (12·5%), with nine (5·7%) clinically significant antibodies. Positive AS occurred more frequently in RhD negative (P=0·021) and in those transfused (P=0·022). Post-transplant positive DAT was associated with piperacillin-tazobactam use (P=0·021) and minor ABO incompatibility (P=0·0038). Five patients presented passenger lymphocyte syndrome (PLS), all received liver-graft O, four presented haemolysis, and three were transfused due to PLS. Auto- and alloantibodies against red blood cell antigens are frequent in LT, but the frequency of immune haemolysis was only 2·8%. The only risk factor for PLS was minor ABO mismatch.

Hybrid glycophorin and red blood cell antigen genotyping in Asian American type O blood donors with Mia phenotype.

The GP.Mur glycophorin with Mia phenotype is relatively common and clinically significant in the Southeast Asian populations. The aim of this study is to genotype Mia -positive Asian American type O blood donors. Red blood cell (RBC) minor antigens were also determined in the same cohort. Asian American blood donors of the Gulf Coast Regional Blood Center (Houston, TX) were screened using a typing reagent (NOVACLONE Anti-Mia Monoclonal IgG Typing Reagent, Dominion Biologicals Ltd) from March 2016 to July 2018. Aliquots of Mia -positive blood from type O donors were subjected to serologic confirmation using Mia - and/or Mur-specific GAMA210 and 64D6 monoclonal antibodies, and two human antisera. Extracted genomic DNA was amplified by polymerase chain reaction (PCR) using GYP hybrid gene/allele-specific primers followed by bidirectional Sanger sequencing. Zygosity for GYP*Mur and GYP*Bun was determined using TaqMan real-time PCR assay. Phenotypes of 35 RBC antigens and three phenotypic variants were determined with use of an in vitro diagnostic test, PreciseType HEA Molecular BeadChip Test (Immucor). By screening 4600 blood donations in the Houston metropolitan area, 209 samples from 103 unique donors were identified to be Mia -positive. By PCR and sequencing analysis, 97 of the 103 Mia -positive donors carried hybrid genes GYP*Mur (89.7% including two homozygotes), GYP*Bun (6.2%), GYP*Vw (3.1%) and GYP*Hut (1.0%). Concordance between serology and DNA analysis was 98%, 99%, and 100% for the GAMA210, 64D6, and human antisera, respectively. Genotyping of RBC antigens showed that the Mia -positive donors were predominantly associated M+ N- S- s+ (48.5%) and M+ N+ S- s+ (38.1%) phenotypes. The GP.Mur glycophorin is most prevalent in the Mia -positive Asian American type O blood donors.

Mechanisms of alloimmunization in sickle cell disease.

Red blood cell (RBC) transfusion is an important treatment for some complications of sickle cell disease (SCD). On the contrary, transfusion may lead to alloimmunization to RBC antigens, with such alloantibodies putting patients at risk for acute or delayed hemolysis, and increasing the difficulty of finding compatible RBCs. Patients with SCD are more susceptible to developing RBC alloantibodies than other multiply transfused patient populations, for reasons that are not completely understood. In this review, we summarize the available data about risk factors and underlying mechanisms associated with RBC alloimmunization in SCD. Although RBC antigen matching between blood donors and transfusion recipients can decrease alloimmunization, complete matching at all loci is not feasible. Patients with SCD show evidence of increased inflammation at baseline and in times of illness. Resultant changes to the innate and adaptive immune systems presumably influence the development of RBC alloantibodies as well as RBC autoantibodies. The inflammation and immune dysregulation associated with SCD may be therapeutic targets for preventing the formation of antibodies and/or for mitigating the dangers of existing RBC alloantibodies. As long as RBC transfusion therapy remains an important treatment for SCD, the quest to improve its safety profile will continue.

Intrauterine Fetal Transfusion

1. A woman is pregnant at 31 weeks’ gestation with Rh (D)–negative, antibody-negative blood type. She develops a placental abruption, prompting delivery of a viable preterm infant with Rh (D)–positive blood type. Which of the following is recommended after delivery to prevent D-alloimmunization in the mother? 2. Unfortunately she does not receive the appropriate treatment. She then has a miscarriage while traveling and has an extremely elevated anti-D antibody titer in her next pregnancy 2 years later. She is diagnosed with fetal anemia at 22 weeks’ gestation and ultimately has a procedure ( Video 1). What procedure is being shown in this video? Video 1. Click here to view the video. Fetal intraperitoneal transfusion. Alloimmunization is the development of antibodies to foreign red blood cell antigens. Fetal red blood cell antigens are determined by maternal and paternal red blood cell phenotypes. If the fetus expresses antigens foreign to the pregnant woman, the woman can develop immunoglobulin G (IgG) antibodies to this …

ID CORE XT as a tool for molecular red blood cell typing

ABSTRACTIntroduction: Classic methods to determine human red blood cell (RBC) antigens are based on serologic testing, however there are some limitations. Based on these, several molecular techniques have been developed to bypass these restrictions and to detect the most important allelic variants, the last of great value for the approach in the personalized medicine, especially for patients in chronic transfusion regime.Areas covered: In this article, we provide an updated review of the ID CORE XT (Progenika Biopharma-Grifols, Bizkaia, Spain) that is one of the commercial DNA-based techniques available to genotyping of RBC antigens.Expert opinion: It is a platform based on Luminex technology with an automated workflow after DNA extraction and its robustness has been shown through validation studies. This technology provides a useful tool to increase the inventory of antigen-negative RBC units, through a mass-scale donor genotyping for RBC antigens and prevent immunization of patients who require chronic transfusion by providing compatible RBC units based on matching by DNA testing.

Blood group genotyping of blood donors: validation of a highly accurate routine method.

In the past century, blood group determination using serology has been the standard method. Now, molecular methods are gaining traction, which provide additional and easily accessible information. Here we designed and validated a high-throughput extended genotyping setup. We developed 35 competitive allele-specific polymerase chain reaction assays for genotyping of blood donors. Samples from 1034 Danish blood donors were genotyped, and 45,314 red blood cell antigens and 6148 platelet antigens were predicted. Predicted phenotypes were compared with 16,119 serologic phenotypes. We found 62 discrepancies of which 43 were due to serology. After exclusion of the discrepancies caused by serology, the accuracy of genotyping was 99.9%. Of 17 discrepancies caused by the genotype, three were incorrect antigen-negative predictions and could potentially, as the solitary analysis, have caused an adverse transfusion reaction. We have established a robust and highly accurate blood group genotyping system with a very high capacity for screening blood donors. The system represents a significant improvement over the former serotyping-only procedure. Almost all new technology in medicine incurs increased costs, but the presented efficient genotyping system is a rare example of a significant qualitative and quantitative technologic progress that is also more cost-efficient than previous technologies.

Alloimmunization of a dog erythrocyte antigen 1- dog transfused with weakly dog erythrocyte antigen 1+ blood.

BackgroundAcute hemolytic transfusion reactions because of dog erythrocyte antigen (DEA) 1 sensitization after mismatched transfusions are serious complications. Dog erythrocyte antigen 1 expression varies from negative to weakly to strongly positive.ObjectivesTo assess alloimmunization after transfusion of weakly DEA 1+ blood to a DEA 1− dog.AnimalsOne DEA 1− recipient and 1 weakly DEA 1+ donor, and 106 control dogs.MethodsLong‐term follow‐up study. Matched for DEA 3, 4, 5, and 7, Dal, and Kai 1 and 2, weakly DEA 1+ donor packed red blood cells (RBCs) were transfused 3 times (0.45 mL/kg at Day 0, 16, and 37) to a DEA 1− recipient. Alloantibodies against RBCs from donor and 106 controls were determined in recipient's plasma samples using a commercial antiglobulin‐enhanced immunochromatographic strip and gel tube crossmatches. Alloantibody titers were determined.ResultsThe DEA 1− recipient was sensitized after 16 days to ≥1657 days after transfusion to weakly DEA 1+ and otherwise matched RBCs. Strong to moderate crossmatch incompatibilities were observed between recipient's plasma and all 61 DEA 1+ crossmatched controls. Moderate to weak incompatibilities were also observed to DEA 1− controls. Anti‐DEA 1 and other alloantibodies were detected over the 4.5 year observation period.Conclusions and Clinical ImportanceBlood from a weakly DEA 1+ donor induces a strong and durable alloimmunization in a DEA 1− recipient dog. Additional alloantibodies developed against yet to be defined RBC antigens. Those results support the recommendation of typing dogs against DEA 1, considering weakly DEA 1+ as immunogenic, and crossmatching all previously transfused dogs.

Rejuvenation of RBCs: validation of a manufacturing method suitable for clinical use.

Rejuvenation of stored red blood cells (RBCs) increases levels of adenosine 5'-triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) to those of fresh cells. This study aimed to optimize and validate the US-approved process to a UK setting for manufacture and issue of rejuvenated RBCs for a multicenter randomized controlled clinical trial in cardiac surgery. Rejuvenation of leukoreduced RBC units involved adding a solution containing pyruvate, inosine, phosphate, and adenine (Rejuvesol, Zimmer Biomet), warming at 37°C for 60 minutes, then "manual" washing with saline adenine glucose mannitol solution. A laboratory study was conducted on six pools of ABO/D-matched units made the day after donation. On Days 7, 21, and 28 of 4 ± 2°C storage, one unit per pool was rejuvenated and measured over 96 hours for volume, hematocrit, hemolysis, ATP, 2,3-DPG, supernatant potassium, lactate, and purines added (inosine) or produced (hypoxanthine) by rejuvenation. Subsequently, an operational validation (two phases of 32 units each) was undertaken, with results from the first informing a trial component specification applied to the second. Rejuvenation effects were also tested on crossmatch reactivity and RBC antigen profiles. Rejuvenation raised 2,3-DPG to, and ATP above, levels of fresh cells. The final component had potassium and hemolysis values below those of standard storage Days 7 and 21, respectively, containing 1.2% exogenous inosine and 500 to 1900 μmoles/unit of hypoxanthine. The second operational validation met compliance to the trial component specification. Rejuvenation did not adversely affect crossmatch reactivity or RBC antigen profiles. The validated rejuvenation process operates within defined quality limits, preserving RBC immunophenotypes, enabling manufacture for clinical trials.

Fatal hemolytic disease of the fetus and newborn caused by anti-Jra antibody: A case report and literature review

The Jra antigen of the JR blood group system is a highly prevalent red blood cell antigen. Although anti-Jra–associated hemolytic disease of the fetus and newborn (HDFN) is generally considered mild-to-moderate, a rare fatal case was recently reported. We report the third example of HDFN-related anti-Jra with fatal outcomes. The clinical significance of anti-Jra antibody as a cause of HDFN should be reassessed.

PB2447 RED CELL ALLOIMMMUNIZATION A RETROSPECTIVE SINGLE CENTRE EXPERIENCE IN AN AREA WITH A LOW INCIDENCE OF HAEMOGLOBINOPATHY:

Background:Alloimmunization to Red Blood Cell (RBC) antigens could become a growing issue owing to increasing transfusion programs and an ageing population. The clinical impact of RBC alloimmunization is likely underestimated. It has been recognized that alloimmunization may compromise the therapeutic effect of RBC transfusion. Alloimmunized patients have an increased risk of serious haemolytic transfusion reactions (HTRs) and may not receive adequate RBC transfusion support due to lack of compatible RBC units. Since recently, alloimmunization is not routinely reported to SHOT and there is comparatively little data of its impact on clinical practice.Aims:Identifying transfusion‐related risk factors of alloimmunization against RBC antigens and correlate alloimmunization to the clinical data.Methods:A retrospective cohort study of all RBC‐alloimmunization in a district hospital (UKAS accredited laboratory) between January 2005 and January 2015. The demographics of the patients with alloantibodies, their medical history, and the transfusion‐related adverse events were examined to explore the concept of RBC alloimmunization itself may contribute to morbidity and mortality. Patients with haemoglobinopathies and palliative leukaemia's were excluded. Laboratory data included patients’ ABO/Rh type, antibody screening results, direct antiglobulin test, and alloantibody and autoantibody specificities. Data concerning transfusion reactions were obtained from the hospitals’ transfusion records. The retrospective study was done to find the incidence and type of RBC alloantibodies and to identify factors such as frequency of transfusion, and their association with the development of clinical complications.Results:The study encompasses all the patient whose immunohematological tests were conducted at the Department of Transfusion Medicine Nine patients were identified over the ten year period. Two cases were excluded due to incomplete data. Of the seven patients that had sufficient data the mean blood component requirements were 4.8 (media 3.4‐ 6.3) whereas platelets (PLT) was 1.2 platelet units (range 2.1 – 3.4) respectively. The number of alloimmunized transfused patients in our centre is < 1% ‐ likely bellow than the 1% to 3% commonly quoted, taking into consideration the frequent occurrence of RBC antibody evanescence ‐. The most frequent antibody specificity was anti‐E, followed by Jkb ‐ Jka −Lua, −D, −C and anti‐Wra. Unsurprisingly, we identify alloimmunization was associated with higher numbers of transfused RBC units (3 vs 6; p = 0.001), as well as with longer time under transfusion (4.3 vs. 8.1 months; p = 0.017) as well as increased mortality, in the scenario of previous malignancy.Summary/Conclusion:The clinical course for each of the reported patients provides insight into the direct and indirect consequences of RBC alloimmunization, where patients experienced delayed HTRs or did not receive needed RBC transfusions. Future work examining the clinical impact of RBC alloimmunization should not only consider HTRs but should also address the potential consequences associated with difficulties in obtaining compatible blood.

PS1595 PREVENTING ALLOIMMUNIZATION OF RECIPIENTS WITH SELECTING OF DONORS BY RED BLOOD CELLS ANTIGENS OF THE RHESUS SYSTEM

Background:In April 2013, the Ministry of Health of the Russian Federation approved an order regulating transfusion therapy in hematology patients only taking into account the compatibility of the donor and recipient for the antigens C, c, E, e, CW.Aims:Assess the effectiveness of organizational measures for the prevention of alloimmunization to antigens of red blood cells in patients receiving intensive hemocomponent therapy.Methods:The results of immunohematological studies were analyzed in 3697 patients: 1961 patients were first admitted for treatment at a hematological clinic from 2007 to 2014; 1736 patients ‐ from 2015 to 2018. Non‐Hodgkin lymphoma was diagnosed in 767 patients, chronic myeloid leukemia in 220, chronic lymphocytic leukemia in 320, acute leukemia in 612, multiple myeloma in 398, myelodysplastic syndrome in 73, aplastic anemia ‐ in 147, other hematologic diseases ‐ in 1160. The studies were performed using equipment and reagents from BioRad (USA).Results:In 2007–2014, antibodies to antigens C, c, E, e, CW of the Rhesus system were detected in hematological patients with a frequency of 0.92%. Due to the phenotypic selection of donors, the level of alloimmunization decreased 2.6 times and amounted to 0.35% in 2015–2018 (χ2 = 3,831; p = 0.05). The frequency of detection of antibodies to antigen C (0.25% and 0.06%, respectively) and to antigen E (0.46% vs 0.12%) decreased four times. The selection for the antigen was carried out in the clinic since 1998, therefore the immunization index for this antigen remained at the same level (0.10% vs 0.12%). The frequency of detection of antibodies to the CW antigen has not changed significantly (0.10% vs 0.06%). Alloantibodies to the antigen e were not detected for the entire observation period.Table. The frequency of detection of antibodies to antigens C, c, E, e, CW in hematological patients in the periods 2007–2014, 2015‐2018.Summary/Conclusion:Phenotypic selection of donors for antigens C, c, E of the Rhesus system is an effective method of preventing aloimmunization of patients receiving intensive hemocomponent therapy. The selection of red blood cells for antigens CW and e has no practical significance.image

Effect of 2Me, DTT, ZAAP and Enzyme on JMH Antigen on the Surface of Human Erythrocytes

To explore the the effects of 2-Me, DTT, papain, pineapple protease and ZZAP on the antigenicity of JMH antigen of human red blood cells (RBC) surface. Firstly, human RBC were treated with 2-Me, DTT, pineapple protease, papain and ZZAP reagents, respectively. The antigenicity of JMH antigen on human RBC surface was detected and analyzed by flow cytometry. Flow cytometric analysis found that compared with level before treatment, the antigenicity of JMH antigen on RBC surface was significantly reduced after 2-Me treatment, the positive rate of JMH antigen: 69.5%±4.5% vs 56.5%±3.4% (t=12.44, P＜0.01); fluorescence intensity: 4906±317 vs 3003±165 (t=11.84, P＜0.01). The antigenicity of JMH antigen on RBC surface significantly increased after DTT treatment, showing the positive rate of JMH antigen: 61.7%±3.8% vs 75.5±4.9% (t=16.57, P＜0.01), fluorescence intensity: 4044±294 vs 4854±319 (t=15.46, P＜0.01). However, both bromelain and papain could significantly reduce the antigenicity of JMH antigen on the RBC surface, Bromelain: the positive rate of JMH antigen: 62.2%±3.8% vs 8.8%±1.2% (t=26.44, P＜0.01), fluorescence intensity: 4263±273 vs 1444±212 (t=19.27, P＜0.01); Papain: the positive rate of JMH antigen: 62.8%±3.6% vs 8.8%±1.5% (t=21.38, P＜0.01), fluorescence intensity: 4389±284 vs 1458±230 (t=17.49, P＜0.01). The flow cytometric analysis revealed that ZZAP treatment significantly reduced the antigenicity of JMH antigen on the RBC surface, the positive rate of JMH antigen: 62.2%±4.4% vs 48.2%±4.1% (t=14.87, P＜0.01), fluorescence intensity: 4106±263 vs 2063±175 (t=17.49, P＜0.01). The treatment with 2-Me can reduce the antigenicity of JMH antigen on human RBC surface. The antigenicity of JMH antigen on human RBC surface increased after DTT treatment. The antigenicity of JMH antigen on human RBC surface significantly reduces after the treatment with pineapple protease or papain. ZZAP treatment can reduce the antigenicity of JMH antigen on the RBC surface.

Evaluation of immunohematology knowledge in hematology trainees.

Canadian hematology trainees are expected to attain clinical knowledge in the subject of red blood cell and platelet antigen systems and the principles of transfusion medicine. However, the relative degree of expertise required in blood bank serology is not well defined. A modified Delphi approach involving 10 Canadian hematology program directors was utilized to identify 12 relevant topics in immunohematology. A multiple-choice exam was developed and validated among hematology trainees from 13 hematology training programs across Canada. A Rasch analysis was used to determine fit of the examination before deploying the exam the following year to ascertain the level of knowledge in hematology trainees. The exam was piloted with 62 hematology trainees. The reliability of the exam was 0.93 with a mean item fit score of 1.01. The exam was able to discriminate between training years and self-rated expertise with better performance attained by more advanced trainees (p < 0.01). No differences were seen between geographic regions. A modified version of the exam was deployed the following year to 85 trainees, with a mean score of 58.9% ± 15.3%. Trainees scored poorest on topics concerning antibody investigations and D variants. A standardized exam for assessing hematology trainees on their expected expertise in transfusion immunohematology has been developed and can be used to assess the efficacy of educational resources provided in the subject. Trainees had a low overall mean score indicating additional educational initiatives are warranted.

Immunogenetic Characteristics of Trans-Baikal Different-Purpose Sheep

The results of the immunogenetic characteristics of Trans-Baikal breed fine-fleece sheep by six blood group systems, including fourteen antigen-specific factors, with respect to the production purposes have been reported. The performed analysis of the immunogenetic parameters of blood revealed similarity in the Bb, Bg, Ca, R, and O antigen-specific factors and remarkable differentiation in the Aa, Ab, Be, and Bi antigens between the wool-and-meat and meat-and-wool sheep. High frequencies of the Bb (0.980), Bi (0.873), Ca (0.932), Ma (0.555), R (0.538), and O (0.910) red blood-cell antigens are typical for the wool-and-meat sheep. The animals with antigens Bd, Be, Bg, and Mb (0.150, 0.278, 0.190, and 0.228, respectively) are rarely found. High concentrations of antigens Bb, Be, Ca, Ma, R, O, and Da (0.960, 0.743, 0.782, 0.812, 0.554, 0.713, and 0.505, respectively) are recorded in meat-and-wool sheep. Low frequencies in occurrence are recorded in the animal carriers of Aa (0.119), Ab (0.109), Bd (0.089), Bi (0.109), Bg (0.129), and Mb (0.149). The Aa, Ab, Bi, Ca, and O antigens are rather often found in the wool-and-meat sheep (P < 0.001), while the meat-and-wool sheep have higher concentrations of Be, Ma, and Da factors (P < 0.001). The genetic identity and distance between the intrabreed specimens comprised 0.652 and 0.428, respectively.

Microbial pathogen primary sequence inversely correlates with blood group antigen immunogenicity.

It is well known that specific groups of patients immunologically respond more readily than others to red blood cell (RBC) antigens. While allogeneic RBC antigen exposure is the primary determinant of alloantibody formation, other variables are also involved. Given the significant primary sequence identity between common RBC and microbial antigens, we hypothesized that certain individuals may be immunologically primed to form RBC alloantibodies via environmental exposure to cross-reactive microbial epitopes, and that such a correlation may be linked to blood group antigen immunogenicity. We examined the relationship between RBC-microbe peptide homology and the formation of alloantibodies to the most immunogenic RBC antigens, using the BLASTp homology database. Thirteen-residue peptides centered on the polymorphic amino acids of K, Jka , Lua , E, c, M, C, and S antigens were queried for identity with microbial peptides using the BLASTp database. Results were restricted to bacteria and fungi, with a selective threshold of >80% identity for inclusion, to allow for minor peptide variability. Significant peptide identity was found between RBC antigens and pathogenic organisms including B. fragilis, P. aeruginosa, and Candida spp., among others. Linear regression and k-medoids clustering analysis of the microbial genera meeting the inclusion criteria showed a statistically significant inverse correlation with RBC immunogenicity (b = -0.0017, r2 = 0.624 & p = 0.0197), with lower immunogenicity antigens associated with larger number of genera. Our findings raise a potential relationship between microbial exposure and alloantibody formation, and lead to interesting questions regarding the potential relationship between RBC antigen immunogenicity and microbial prevalence.

Red blood cell alloimmunization and delayed hemolytic transfusion reactions in patients with sickle cell disease

Red blood cell (RBC) alloimmunization is more common in patients with sickle cell disease (SCD) than in any other studied patient population. The high prevalence of RBC alloimmunization is multi-factorial, likely involving the chronic hemolysis and inflammatory status of SCD itself, the transfusion burden of patients, and the RH genetic diversity of patients and blood donors, among other reasons. Antibody evanescence, or the decrease of RBC alloantibodies below levels detectable by blood bank testing, occurs frequently with fewer than 30% of alloantibodies estimated to be detected by current screening practices. Evanescence increases the likelihood that a patient with SCD will have a delayed hemolytic transfusion reaction upon future RBC exposure, with previously undetected alloantibodies coming roaring back in an anamnestic manner after exposure to the cognate RBC antigen. A subset of patients having delayed hemolytic transfusion reactions go on to experience hyperhemolysis; some but not all cases of hyperhemolysis are associated with previously evanescent RBC alloantibodies. There is an increasing appreciation of the association between RBC alloantibodies and RBC autoantibodies, as well as involvement of the alternative complement pathway in some instances of hyperhemolysis. A case report in this manuscript describes a highly alloimmunized patient with SCD who experiences a delayed hemolytic transfusion reaction with bystander hemolysis due to a previously evanescent, complement binding anti-M RBC alloantibody. Additional studies, including those involving multiple centers and countries, are needed to further understand RBC alloimmunization in patients with SCD and to develop strategies to prevent or mitigate potentially life-threatening hemolytic transfusion reactions.