Evaluation of Platelet Alloimmunization by Filtration Enzyme-Linked Immunosorbent Assay

The current methods for detecting antiplatelet antibodies are mostly manual and labor-intensive. A convenient and rapid detection method is required for effectively detecting alloimmunization during platelet transfusion. In our study, to detect antiplatelet antibodies, positive and negative sera of random-donor antiplatelet antibodies were collected after completing a routine solid-phase red cell adherence test (SPRCA). Platelet concentrates from our random volunteer donors were also prepared using the ZZAP method and then used in a faster, significantly less labor-intensive process, a filtration enzyme-linked immunosorbent assay (fELISA), for detecting antibodies against platelet surface antigens. All fELISA chromogen intensities were processed using ImageJ software. By dividing the final chromogen intensity of each test serum with the background chromogen intensity of whole platelets, the reactivity ratios of fELISA can be used to differentiate positive SPRCA sera from negative sera. A sensitivity of 93.9% and a specificity of 93.3% were obtained for 50 μL of sera using fELISA. The area under the ROC curve reached 0.96 when comparing fELISA with the SPRCA test. We have successfully developed a rapid fELISA method for detecting antiplatelet antibodies.

CMV screening of group-specific orders-good stewardship of the blood supply

BACKGROUND

In addition to antigen-negative red blood cells (RBC), Immunohematology Reference Laboratories (IRL) must provide RBCs that are cytomegalovirus (CMV) seronegative. Due to high percentage of CMV seropositive individuals, it is challenging to find CMV and antigen-negative RBC. The IRL selects predominantly group O donors tested for CMV, and these RBC are sometimes needed to fill orders for nongroup O patients. This study evaluated units sent that were out of group to fulfill CMV-seronegative requests.

STUDY DESIGN AND METHODS

Requests for CMV-seronegative and antigen-negative RBCs were divided into Period 1 (January 1, 2019-February 29, 2020) before intervention and Period 2 (March 1, 2020-May 31, 2020) post intervention. ABO Rh units requested were compared to ABO Rh units provided.

RESULTS

Period 1: 537 CMV-seronegative RBC units were provided. 99/188(52.66%) B-positive requests were fulfilled using O RBCs. 58/504 (11.51%) of D-negative units were sent to D-positive patients. Period 2: 119 CMV-seronegative RBC units were provided. 18/51 (35.29%) B positive requests were fulfilled using O RBCs. Only 7/113 (6.19%) D-negative units were sent to D-positive patients.

DISCUSSION

For 239/656 (36.43%) CMV-seronegative antigen orders requested for B-positive patients, more than half of these orders were filled with O RBCs. To decrease group O usage for nongroup O patients, the IRL practice has changed to increase CMV testing for group B donors. Since the change in algorithm, there was a 17.37% decrease group O usage for group B patients.

Retrospective Study on Prevalence, Specificity, Sex, and Age Distribution of Alloimmunization in Two General Hospitals in Athens

Objective:

Blood transfusion is a common lifesaving treatment but it is often complicated with alloimmunization. Previously studies in Greece have concentrated on alloimmunization in multiply transfused thalassemic patients or antenatal women. However, the relative frequency of red blood cell (RBC) alloantibodies in the general patient population has not been studied so far. The aim of the present retrospective study was to estimate the prevalence and specificity of RBC alloantibodies in a large cohort of patients in two general hospitals and their association with age, sex, and the patients’ clinic of hospitalization.

Materials and Methods:

Data from 2012 to 2016 from the “Sismanogleio” and “Thriasio” general hospitals in Athens, Greece, were studied retrospectively. Statistical analysis was performed with SAS for Windows 9.4.

Results:

Six hundred twenty-six patients (626/53800, 1.16%) were alloimmunized for one or more alloantibodies. The mean age was 67.99±17.56 years. Most antibodies were found in women [62.66% (438/699) in women vs. 37.34% (261/699) in men (p=0.0007)], while the vast majority of antibodies (66.81%) were found in patients aged 61-90. The most frequent antibody was anti-Kell (26.61%), followed by anti-E (16.02%), anti-D (15.02%), anti-Jka (5.87%), and anti-M (5.72%). Anti-C (81.48%, n=27) and anti-Cw (54.17%, n=24) tended to be found more often in patients with multiple antibodies. Most alloimmunized cases were found in general surgery (42.65%) and internal medicine departments (38.66%).

Conclusion:

According to our results, the alloimmunization data in a general patient population in Greece were consistent with the majority of studies in the international literature. Whether a strategy at national level needs to be directed towards extending matching for the whole population or towards applying sensitive and compulsory indirect antiglobulin tests before any transfusions in order to efficiently prevent alloimmunization remains an issue of debate.

Selecting red blood cell units to perform RBCX in patients with sickle cell disease

Red blood cell exchange (RBCX) is a standard option for treating or preventing complications in patients with sickle cell disease (SCD). According to the patient's blood volume, the amounts of red blood cells (RBC) to be exchanged and the practices of the apheresis and clinical teams, such treatment requires numerous red blood cell units (RBCUs) (3-15 RBCUs per procedure). To perform RBCXs safely and prevent the risk of alloimmunization, appropriate RBCUs must be selected and transfused to replace the sickled RBCs. Understanding of alloimmunization in patients with SCD strengthened the development of recommendations for preventing the risk of alloimmunization. This review describes the alloimmunization risk, the methods used to decrease the risk, and our own experience.

Red blood cell exchange in patients with sickle cell disease-indications and management: a review and consensus report by the therapeutic apheresis subsection of the AABB

BACKGROUND

A prior practice survey revealed variations in the management of patients with sickle cell disease (SCD) and stressed the need for comprehensive guidelines. Here we discuss: 1) common indications for red blood cell exchange (RCE), 2) options for access, 3) how to prepare the red blood cells (RBCs) to be used for RCE, 4) target hemoglobin (Hb) and/or hematocrit (Hct) and HbS level, 5) RBC depletion/RCE, and 6) some complications that may ensue.

STUDY DESIGN AND METHODS

Fifteen physicians actively practicing apheresis from 14 institutions representing different areas within the United States discussed how they manage RCE for patients with SCD.

RESULTS

Simple transfusion is recommended to treat symptomatic anemia with Hb level of less than 9 g/dL. RCE is indicated to prevent or treat complications arising from the presence of HbS. The most important goals are reduction of HbS while also preventing hyperviscosity. The usual goals are a target HbS level of not more than 30% and Hct level of less than 30%.

CONCLUSION

Although a consensus as to protocol details may not be possible, there are areas of agreement in the management of these patients, for example, that it is optimal to avoid hyperviscosity and iron overload, that a target Hb S level in the range of 30% is generally desirable, and that RCE as an acute treatment for pain crisis in the absence of other acute or chronic conditions is ordinarily discouraged.

Noninvasive buccal swab antigen sample and molecular testing provides extended antigen typing for patients with hemoglobinopathies

OBJECTIVE

To demonstrate the feasibility of performing a noninvasive, molecular-based red blood cell (RBC) antigen test on infants and very young children with sickle cell disease as part of a statewide newborn screening follow-up program.

STUDY DESIGN

A prospective pilot project was conducted using a noninvasive buccal swab and test kit to perform DNA-based, extended RBC phenotyping in 92 children participating in a newborn hemoglobinopathy screening follow-up program. Reported data include the extended panel of antigens detected by molecular analysis compared with unaffected population estimates.

RESULTS

Molecular-based RBC antigen testing was successful, with extended RBC typing generated for all subjects. Molecular testing detected several rare negative or rare positive phenotypes, demonstrating the utility of obtaining an extended antigen panel.

CONCLUSION

This study demonstrates the feasibility of performing antigen testing on buccal swab specimens from children with sickle cell disease as part of a newborn screening follow-up program with the aim of allowing specific unit matching to prevent alloimmunization with RBC transfusions. The general applicability of testing may be limited by a lack of uniform insurance coverage for buccal swab testing, however.

Prevalence and Specificity of RBC Alloantibodies in Indian Patients Attending a Tertiary Care Hospital

Background. Red blood cell (RBC) alloimmunization results from genetic disparity of RBC antigens between donor and recipients. Data about alloimmunization rate in general patient population is scarce especially from resource limited countries. We undertook this study to determine prevalence and specificity of RBC alloantibodies in patients admitted in various clinical specialties at a tertiary care hospital in North India. Methods. Antibody screening was carried out in 11,235 patients on automated QWALYS 3 platform (Diagast, Loos, France). Antibody identification was carried out with an 11-cell identification panel (ID-Diapanel, Diamed GmbH, Switzerland). Results. The overall incidence of RBC alloimmunization in transfused patients was 1.4% (157/11235), with anti-E being the most common specificity (36.3%), followed by anti-D (16%), anti-c (6.4%), anti-c + E (6.4%), anti-C + D (5.1%), and anti-K (4.5%). The highest incidence of alloimmunization was observed in hematology/oncology patients (1.9%), whereas in other specialties the range was 0.7–1%. Conclusion. As alloimmunization complicates the transfusion outcomes, authors recommend pretransfusion antibody screening and issue of Rh and Kell matched blood to patients who warrant high transfusion requirements in future.

HLA-DRB1*07:01 allele is primarily associated with the Diego a alloimmunization in a Brazilian population

BACKGROUND

The Diego blood group presents a major polymorphic site at Residue 854, causing a proline (Di(b) antigen) to leucine (Di(a) antigen) substitution. Di(a) alloimmunization has been observed among Asian and Native South American populations. Considering that Brazilians represent a genetically diverse population, and considering that we have observed a high incidence of Di(a) alloimmunization, we typed HLA-DRB1 alleles in these patients and performed in silico studies to investigate the possible associated mechanisms.

STUDY DESIGN AND METHODS

We studied 212 alloimmunized patients, of whom 24 presented immunoglobulin G anti-Di(a) , 15 received Di(a+) red blood cells and were not immunized, and 1008 were healthy donors. HLA typing was performed using commercial kits. In silico analyses were performed using the TEPITOPEpan software to identify Diego-derived anchor peptide binding to HLA-DRB1 molecules. Residue alignment was performed using the IMGT/HLA for amino acid identity and homology analyses.

RESULTS

HLA-DRB1*07:01 allele was overrepresented in Di(a) -alloimmunized patients compared to nonimmunized patients and to healthy donors. Two motifs were predicted to be potential epitopes for Di(a) alloimmunization, the WVVKSTLAS motif was predicted to bind several HLA-DR molecules, and the FVLILTVPL motif exhibited highest affinity for the HLA-DRB1*07:01 molecule. Pocket 4 of the DRB1*07:01 molecule contained specific residues not found in other HLA-DRB1 molecules, particularly those at Positions 13(Y), 74(Q), and 78(V).

CONCLUSION

Individuals carrying the HLA-DRB1*07:01 allele present an increased risk for Di(a) alloimmunization. The identification of susceptible individuals and the knowledge of potential sensitization peptides are relevant approaches for transfusion care, diagnostic purposes, and desensitization therapies.

Mononuclear cells from a rare blood donor, after freezing under good manufacturing practice conditions, generate red blood cells that recapitulate the rare blood phenotype

BACKGROUND

Cultured red blood cells (cRBCs) from cord blood (CB) have been proposed as transfusion products. Whether buffy coats discarded from blood donations (adult blood [AB]) may be used to generate cRBCs for transfusion has not been investigated.

STUDY DESIGN AND METHODS

Erythroid progenitor cell content and numbers and blood group antigen profiles of erythroblasts (ERYs) and cRBCs generated in human erythroid massive amplification (HEMA) culture by CB (n = 7) and AB (n = 33, three females, three males, one AB with rare blood antigens cryopreserved using CB protocols) were compared.

RESULTS

Variability was observed both in progenitor cell content (twofold) and number of ERYs generated (1 log) by CB and AB in HEMA. The average progenitor cell contents of the subset of AB and CB analyzed were similar. AB generated numbers of ERYs three times lower (p < 0.01) than CB in HEMA containing fetal bovine serum but similar to CB in HEMA containing human proteins. Female AB contained two times fewer (p < 0.05) erythroid progenitor cells but generated numbers of ERYs similar to those generated by male AB. Cryopreserved AB with a rare blood group phenotype and shipped to another laboratory generated great numbers of ERYs, 90% of which matured into cRBCs. Blood group antigen expression was consistent with the donor genotype for ERYs generated both by CB and AB but concordant with that of native RBCs only for cells derived from AB.

CONCLUSION

Buffy coats from regular donors, including a donor with rare phenotypes stored under conditions established for CB, are not inferior to CB for the generation of cRBCs.

The National Heart, Lung, and Blood Institute Recipient Epidemiology and Donor Evaluation Study (REDS-III): a research program striving to improve blood donor and transfusion recipient outcomes

BACKGROUND

The Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) is a 7-year multicenter transfusion safety research initiative launched in 2011 by the National Heart, Lung, and Blood Institute.

STUDY DESIGN AND METHODS

The domestic component involves four blood centers, 12 hospitals, a data coordinating center, and a central laboratory. The international component consists of distinct programs in Brazil, China, and South Africa, which involve US and in-country investigators.

RESULTS

REDS-III is using two major methods to address key research priorities in blood banking and transfusion medicine. First, there will be numerous analyses of large "core" databases; the international programs have each constructed a donor and donation database while the domestic program has established a detailed research database that links data from blood donors and their donations, the components made from these donations, and data extracts from the electronic medical records of the recipients of these components. Second, there are more than 25 focused research protocols involving transfusion recipients, blood donors, or both that either are in progress or are scheduled to begin within the next 3 years. Areas of study include transfusion epidemiology and blood utilization, transfusion outcomes, noninfectious transfusion risks, human immunodeficiency virus-related safety issues (particularly in the international programs), emerging infectious agents, blood component quality, donor health and safety, and other donor issues.

CONCLUSIONS

It is intended that REDS-III serve as an impetus for more widespread recipient and linked donor-recipient research in the United States as well as to help assure a safe and available blood supply in the United States and in international locations.

Chimerism in transfusion medicine: the grandmother effect revisited

Transfusion therapy is complicated by the production of alloantibodies to antigens present in the donor and lacking in the recipient through the poorly-understood but likely multi-factorial process of alloimmunization. The low prevalence of alloimmunization in transfused patients (6.1%) (1) suggests that processes central to immunologic tolerance may be operating in the vast majority of transfused patients who do not produce alloantibodies. Using RhD as a prototype, evidence is reviewed that the ability to make antibodies to red blood cell (RBC) antigens may result in part from immunologic tolerance acquired in utero. These ideas are extended to other examples of maternal microchimerism (MMc) of other non-inherited maternal antigens (NIMA). An evolutionary argument is offered that multi-generational immunity supports the hypothesis that MMc may partly explain the "non-responder" phenotype in RBC alloimmunization.