Which RhD alleles are risk factors stimulating allo- anti-D?

The aim of this study was to identify the specific RhD alleles that are risk factors for stimulating allo-anti-D and develop a precise strategy for blood transfusion. To confirm the D phenotype, red blood cells suspended in saline should react to serological anti-D from three manufacturers. An antibody screen test, a saline phase test and a micro-column test were conducted to identify allo-anti-D and other allo-antibodies. RhD alleles were genotyped by PCR using sequence-specific primers. Seven hundred subjects who were either pregnant or had undergone transfusion were enrolled in our study; however, 28 samples were excluded because their RhD alleles were normal, as revealed by tests using genotyping kits. A total of 498 cases (74.1%) were RhD-null (lacking exons 1–10 of RhD), 336 were DEL RhD 1227A (20.2%), and 38 were RHD-CE (2-9) -D (5.6%). There were 136 cases (20.2%) with allo-anti-D among the 672 cases, with an allo-anti-D prevalence of 126 cases (25.3%) in 498 cases that were RhD-null, followed by 10 cases (26.3%) among 38 cases with RHD-CE (2-9) -D, and none in 366 cases with RhD1227A. RhD genetic polymorphism was observed in RhD-negative individuals. We concluded that RhD-null and partial D are risk factors for alloimmunization to the D antigen and should be transfused with Rh-negative blood. RHD1227A recipients can be transfused with RhD-positive blood. Pregnant women with the d/d and D-CE(2-9)-D alleles require appropriate anti-D prophylaxis and RhD1227A may induce a higher tolerance.     

Human anti-rhesus D IgG1 antibody produced in transgenic plants

Transgenic plants represent an alternative to cell culture systems for producing cheap and safe antibodies for diagnostic and therapeutic use. To evaluate the functional properties of a plantibody, we generated transgenic Arabidopsis plants expressing full-length human IgG1 against the Rhesus D antigen, which is responsible for alloimmunization of RhD– mothers carrying an RhD+ fetus. Anti-RhD extracted from plants specifically reacted with RhD+ cells in antiglobulin technique, and elicited a respiratory burst in human peripheral blood mononuclear cells. Plant-derived antibody had equivalent properties to CHO cell-produced anti-RhD antibody, indicating its potential usefulness in diagnostic and therapeutic programs.     

Generation of ‘designer erythroblasts’ lacking one or more blood group systems from CRISPR/Cas9 gene-edited human-induced pluripotent stem cells

Despite the recent advancements in transfusion medicine, red blood cell (RBC) alloimmunization remains a challenge for multiparous women and chronically transfused patients. At times, diagnostic laboratories depend on difficult-to-procure rare reagent RBCs for the identification of different alloantibodies in such subjects. We have addressed this issue by developing erythroblasts with custom phenotypes (Rh null, GPB null and Kx null/Kell low) using CRISPR/Cas9 gene-editing of a human induced pluripotent stem cell (hiPSC) parent line (OT1-1) for the blood group system genes: RHAG, GYPB and XK. Guide RNAs were cloned into Cas9-puromycin expression vector and transfected into OT1-1. Genotyping was performed to select puromycin-resistant hiPSC KOs. CRISPR/Cas9 gene-editing resulted in the successful generation of three KO lines, RHAG KO, GYPB KO and XK KO. The OT1-1 cell line, as well as the three KO hiPSC lines, were differentiated into CD34⁺CD41⁺CD235ab⁺ hematopoietic progenitor cells (HPCs) and subsequently to erythroblasts. Native OT1-1 erythroblasts were positive for the expression of Rh, MNS, Kell and H blood group systems. Differentiation of RHAG KO, GYPB KO and XK KO resulted in the formation of Rh null, GPB null and Kx null/Kell low erythroblasts, respectively. OT1-1 as well as the three KO erythroblasts remained positive for RBC markers—CD71 and BAND3. Erythroblasts were mostly at the polychromatic/ orthochromatic stage of differentiation. Up to ~400-fold increase in erythroblasts derived from HPCs was observed. The availability of custom erythroblasts generated from CRISPR/Cas9 gene-edited hiPSC should be a useful addition to the tools currently used for the detection of clinically important red cell alloantibodies.     

Human RBC alloimmunization evaluation after exposure to foreign E antigen of the rhesus system in transfusion

Anti-E alloantibody has been one of the most frequently detected clinically significant alloantibodies in previous studies. Red blood cell (RBC) transfusion is unique in its common intravenous introduction of foreign E antigen and provides a valuable opportunity to study the human immunologic response to intravenous foreign E antigen. Patients exposed to foreign E antigen while receiving RBC transfusions are at risk of forming anti-E alloantibody. Valid estimates of anti-E alloimmunization risk are clinically important, but the forming mechanism of anti-E alloimmunization remains unclear. Here, we screened 516 inpatients at risk of exposure to foreign E antigen while receiving RBC transfusions and monitored the development of anti-E alloantibody for up to two years after left hospital. However, only 2 cases of anti-E alloimmunization were identified in this study. Patients who received RBC transfusion had a very high risk of exposure to foreign E antigen, but the anti-E alloantibody production incidence was very low and few anti-E alloantibodies were produced within 3 to 6 months after RBC transfusion in this study. Further research would contribute to our knowledge of the anti-E alloimmunization mechanism and prevent anti-E development, which would be significantly useful in clinical for transfusions, obstetric management, and the evaluation and management of transfusion reactions in laboratory and institutional resources and cost reduction in healthcare system.     

Incidence of unexpected red blood cell antibodies in the north of China

This study aimed to investigate the frequency of unexpected antibodies and evaluate the cumulative incidence of additional unexpected antibodies in Beijing. From January 1, 2011 to December 31, 2014, blood samples from 2,095 patients from 98 medical institutes in Beijing were sent to the Beijing Red Cross Blood Center for antibody identification. Of the unexpected antibodies, 29.5% were autoantibodies and 70.5% were alloantibodies. Anti-E was the most prevalent form of allo-antibodies (n = 445), accounting for 52.9% of the Rh system, followed by anti-M (76.6% of the MNS system) and then 142 cases of anti-C,e, 128 cases of anti-E,c, and 113 cases of anti-Lea. The cumulative incidences of additional antibodies were 0.55% (after the first transfusion), 1.82% (second time), 2.33% (fourth time), 3.07% (firth time), and 4.24% (seventh time). Antibody against the Rh system was the most prevalent, followed by antibodies against MNS, Lewis, Kidd, P1, and Duffy.     

Frequency of unexpected red blood cell antibodies in Nanjing

The development of unexpected red blood cell antibodies can significantly complicate transfusion therapy and result in more difficulties in cross-matching of blood. This study aimed to determine the occurrence rate of red blood cell alloimmunization in patients from Nanjing and the surrounding area. The antibody screening tests were carried out on 604 patients in Nanjing Red Cross Blood Center from January 2014 to December 2016, and the results were compiled and statistically analyzed. In the 604 patients, 483 cases revealed autoantibodies with or without underlying alloantibodies, while 121 patients had only alloantibodies in their serum. The overall frequency of alloimmunization was 32.5%. The most frequent antibodies were what against the Rh systerm(72.39%), followed by MN system (25.71%).     

Management and cause analysis of platelet transfusion refractoriness

Platelet transfusion refractoriness (PTR) can be defined as the less increment of platelet count than expected after platelets transfusion, which is a challenging and expensive problem often observed in platelet-transfusion-dependent patients. Although PTR occurs most frequently due to non-immune causes, a significant minority is still caused by immune factors. The most important factor in immune dependent PTR is alloimmunization against Class I human leukocyte antigens (HLAs) or human platelet antigens (HPAs). The compatible platelets can be provided to immune-mediated patients using platelet crossmatching, HLA matching, and antibody specificity testing. These measures-aimed to eliminate donor-specific HLA antibodies will lead to the improved clinical management of PTR patients, caused by severe alloimmunization.     

Association of sex, age and ABO-Rh(D) type with unexpected antibodies among multitransfused thalassemia patients in Bikaner, Rajasthan, India

The thalassemia has become a sensitive issue for clinical and public health owing to the morbidity and mortality caused and potential risks associated with multiple transfusions. Here, a blood bank based cross sectional analytical study was carried out during the period of three months from January 2017 to March 2017, among transfusion dependent beta thalassemia major patients. ABO-Rh(D) blood grouping and screening for unexpected red cell antibodies (other than anti-A and anti-B antibodies) were performed on a Immucor Galileo Neo System (fully automated immunohematology analyzer). Out of 56 patients, 37 (66%) were males and 19 (34%) were females with a male to female ratio of 1.95:1. Two cases (3.6%) were detected positive by antibody screening. Alloimmunization was statistically analyzed on the basis of age, sex and subjects'' ABO-Rh blood group. This study underlines the need for unexpected antibody screening among thalassemic patients receiving blood transfusion therapy.