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Background and Objectives: The identification of platelet antibodies is essential for diagnosing and managing conditions such as fetal and neonatal alloimmune thrombocytopenic purpura, post-transfusion purpura, and immune platelet refractoriness. Monoclonal antibody immobilization of platelet antigens (MAIPA) is the standard method for detecting anti-human platelet antigen (HPA) antibodies, while the detection of anti-HLA antibodies once relied on the complement-dependent cytotoxicity method, however advanced technologies such as enzyme-linked immunosorbent assay and Luminex have significantly improved sensitivity and accuracy in identifying these antibodies. Flow cytometry-based techniques (platelet immunofluorescence test - PIFT) and Luminex platform-driven microsphere-based multiplex assays (Pak-Lx) are widely employed in platelet immunology laboratories owing to their remarkable flexibility and versatility. The present study compared the sensitivity, specificity, and concordance of these different serological techniques used in platelet antibody identification. Material and Methods: One hundred serum samples from patients suspected of immune-mediated platelet disorders were examined. Initially, the samples underwent testing using the MAIPA method. Subsequently, the results were compared with three alternative methods: PIFT and microsphere-based multiplex assays for both HLA and HPA antibodies. Results: Pak-Lx demonstrated a 94 % agreement with MAIPA, while PIFT had 88 % agreement for HPA antibodies. For HLA antibody detection, Pak-Lx versus DLX had 75 % concordance, MAIPA versus DLX showed 77 %, and PIFT versus DLX displayed an 81 % concordance rate. Remarkably, there were no significant differences in concordance levels between Pak-Lx and PIFT compared to MAIPA and DLX for anti-HPA and HLA antibodies, respectively. Conclusion: This study found no significant differences in concordance among the tested assays for detecting anti-HPA and anti-HLA antibodies. These data suggest that no single method can detect all clinically important antibodies. Therefore, it is advisable that each laboratory develops customized protocols based on their expertise and employs complementary methods for comprehensive patient assessments.

Background and Objectives: The identification of platelet antibodies is essential for diagnosing and managing conditions such as fetal and neonatal alloimmune thrombocytopenic purpura, post-transfusion purpura, and immune platelet refractoriness. Monoclonal antibody immobilization of platelet antigens (MAIPA) is the standard method for detecting anti-human platelet antigen (HPA) antibodies, while the detection of anti-HLA antibodies once relied on the complement-dependent cytotoxicity method, however advanced technologies such as enzyme-linked immunosorbent assay and Luminex have significantly improved sensitivity and accuracy in identifying these antibodies. Flow cytometry-based techniques (platelet immunofluorescence test - PIFT) and Luminex platform-driven microsphere-based multiplex assays (Pak-Lx) are widely employed in platelet immunology laboratories owing to their remarkable flexibility and versatility. The present study compared the sensitivity, specificity, and concordance of these different serological techniques used in platelet antibody identification., Material and Methods: One hundred serum samples from patients suspected of immune-mediated platelet disorders were examined. Initially, the samples underwent testing using the MAIPA method. Subsequently, the results were compared with three alternative methods: PIFT and microsphere-based multiplex assays for both HLA and HPA antibodies., Results: Pak-Lx demonstrated a 94 % agreement with MAIPA, while PIFT had 88 % agreement for HPA antibodies. For HLA antibody detection, Pak-Lx versus DLX had 75 % concordance, MAIPA versus DLX showed 77 %, and PIFT versus DLX displayed an 81 % concordance rate. Remarkably, there were no significant differences in concordance levels between Pak-Lx and PIFT compared to MAIPA and DLX for anti-HPA and HLA antibodies, respectively., Conclusion: This study found no significant differences in concordance among the tested assays for detecting anti-HPA and anti-HLA antibodies. These data suggest that no single method can detect all clinically important antibodies. Therefore, it is advisable that each laboratory develops customized protocols based on their expertise and employs complementary methods for comprehensive patient assessments., Competing Interests: Conflicts of interest I declare that I am not subject to any kind of conflict of interest with participants or any other collaborator, directly or indirectly, for the development of the Research Project entitled ‘Platelet antibody detection assays: a single-laboratory comparison of MAIPA, PIFT, and microsphere-based multiplex assays Pak-Lx’ whose involved researchers are: Thiago Henrique Costa, Carolina Bonet Bub and José Mauro Kutner., (Copyright © 2024 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier España, S.L.U. All rights reserved.)

Serological methods for antiplatelet antibody determination have contributed to the understanding and better diagnosis of immune mediated thrombocytopenia. Although most tests for determination of antiplatelet antibodies were initially introduced for antibody detection in patients with idiopathic thrombocytopenic purpura, nowadays these methods are used in the diagnosis of platelet disorders when an immune pathomechanism is suspected. Serological testing is mostly used in the diagnosis of foetal and neonatal alloimmune thrombocytopenia, post-transfusion thrombocytopenic purpura and platelet transfusion refractoriness and of primary and secondary autoimmune thrombocytopenia. Development of molecular biology has enabled more accurate determination of platelet antigens and assessment of their prevalence in the population. These advancements have upgraded evaluation of the role of particular antigen systems in the etiology of auto- and alloimmune thrombocytopenic syndromes, association of human platelet antigen polymorphisms with susceptibility to cardiac and cerebrovascular diseases, and outcome of allogeneic bone marrow and solid organ transplantation. [ABSTRACT FROM AUTHOR]

Human platelet antibody (HPA) detection is necessary for the diagnosis and therapeutic decisions for refractoriness to platelet transfusions, post transfusion purpura and fetal and neonatal alloimmune thrombocytopenia. In the last four to five decades many new developments, both in knowledge and methods, have increased the quality of platelet serology. However, the quest for the optimal antibody detection method(s) encountered, sometimes unexpected, difficulties. In this review the various aspects concerning platelet antibody test methods and detection of platelet antibodies both for the diagnostic and screening setting are discussed. [ABSTRACT FROM AUTHOR]

Background: Human platelet alloantigen (HPA) is part of the platelet membrane structure, named HPA1- 17 system. This study aimed to investigate platelet alloimmunity in the Achang and Jingpo population, ethnic minority specific, to establish a typed platelet donor data bank in Yunnan's ethnic minority areas., Methods: In this study, samples from 139 unrelated healthy cases from the Achang population, 148 cases of the Jingpo population, and 150 healthy cases from Yunnan's Han population were collected as a control. PCR-sequence specific primers (PCR-SSP) methods were respectively adopted to genotype HPA-1-17. The frequency of genes and genotypes was calculated separately, and the frequency distribution of alleles in the Achang population was compared with that of the Han population., Results: Monomorphic HPA-7-14 and HPA-16 and 17 were found in the samples from the Han population, while HPA-b was not found in any of these samples. In HPA-1, 2, 4, 5, and 6, aa homozygosity was predominant. Monomorphic HPA-7, HPA-9-14 and HPA-16 were found in the samples from the Achang population, while HPA-b was not found. In HPA-1, 2, 4, 5, 6, 8, and 17, aa homozygosity was predominant. The genotype results of the HPA-4, 7, HPA9-12, HPA14, 16-17 antigen systems in the Jingpo population were all aa, while the HPA-b was not detected. In HPA-1, 2, 5, 6, 8 and 13, aa homozygosity was predominant. HPA-3, 15 showed the greatest heterozygosity among the three populations. The frequency of HPA-1a in the Achang population in Yunnan was significantly different from that in the Han population (P<0.05). There was no difference in the HPA system of the Jingpo population, but the HPA-2a system was different between the Achang and Jingpo populations (P<0.05)., Conclusions: In Yunnan, the distribution of the allele polymorphism of HPA-1-17 in the Achang and Jingpo population is similarly distributed to that in the Han population and exhibits their own characteristic. Therefore, a database of platelet donor typing of the ethnic group should be established.

In fetal/neonatal alloimmune thrombocytopenia (FNAIT), platelets are destroyed by maternal antibodies directed against fetal/neonate antigens. Thrombocytopenia can be severe and lead to intracranial hemorrhage (ICH) in about 10% of cases. Although three types of antigen groups, presented on platelets [ABO blood group antigens, human leukocyte antigens (HLA) and human platelet antigens (HPA)] are known to be implicated in immune platelet destruction, antibodies against HPA are most commonly involved in FNAIT and hence are the target of extensive research. Awareness of FNAIT by physicians as well as the availability of the most sensitive diagnostic methods capable of detecting a wide range of antibodies are crucial for the diagnosis of FNAIT and the prevention of severe thrombocytopenia and its bleeding risks in subsequent pregnancies. [ABSTRACT FROM AUTHOR]