Causes of HLA-A2 reactive antibodies and analysis of their eplets / 中国输血杂志

【Objective】 To analyze differences of eplets between the patient who generated HLA allele-specific antibodies after platelet transfusion with donors. 【Methods】 The HLA genotypes of the patient and donors were detected by PCR-SBT, and the Luminex single antigen beads coating was used to screen HLA-Ⅰ antibodies in the patient’s serum. HLA Matchmaker was utilized to analyze different amino acids and eplets. 【Results】 The patient carried HLA-A*02∶03 allele, and HLA-A2 antibodies were found in his serum after platelet transfusion (A*02∶01, A*02∶06, and A*02∶07). Sequence alignment showed that the patient′s A*02∶03 has a difference in position 149, which resulted in a different eplet between A*02∶03 and A*02∶01, A*02∶06, A*02∶07 and then induced the production of antibodies. 【Conclusion】 HLA antibodies are specific for HLA epitopes that have structural differences due to amino acid differences between HLA alleles, suggesting that high-resolution typing of HLA-A, -B need to be conducted in patients and donors, and the acceptable mismatch of HLA should be determined based on epitopes rather than antigens, so as to reduce alloimmune response and improve platelet count after transfusion.

Analysis of HLA allele-specific antibodies and Eplets in patients with platelet transfusion refractoriness / 中国输血杂志

【Objective】 To analyze the specificity and Eplets of HLA allele-specific antibody in patients with platelet transfusion refractoriness (PTR). 【Methods】 HLA-A and B genotypes were detected by PCR-SBT, and HLA-Ⅰ antibodies in patients′ serum were detected by Luminex single antigen beads coating method. IPD-IMGT/HLA Database was used to find the differential amino acids of allele-specific antibodies, and HLA Eplet database was used to analyze the registry Eplets. 【Results】 HLA allele-specific antibodies were found in 12 out of 82 patients with PTR.After sequence alignment, a total of 18 differential amino acids were found, such as 19E>19K, 166D>116E, 167G>167W and so on. Among these differential amino acids, 16 registry Eplets were retrieved such as 19E>19K, 95I>95L, 113YD>113HD and so on.The amino acid substitution of 166DG>166EW, 70Q>70H, 67S>67Y, 94I>94T, 82LR>82RG, and 211G>211A may form new Eplets that have not been registered.The antigens of A11, A24, B15, B27 and B38 can be further subdivided into HLA narrow specific antigens. 【Conclusion】 It was found that there were HLA allele-specific antibodies in patients with PTR, suggesting that high-resolution typing of HLA-A, B should be carried out for these patients and platelet donors in HLA compatible transfusion of PTR.