External quality assessment of platelet serology and human platelet antigen genotyping: a 10‐year review

Abstract

In this review, the results of an external quality assessment (EQA) over 10 years of platelet (PLT) serology and of human platelet antigen (HPA) polymorphisms genotyping are shown. The detection and identification of PLT antibodies and the distinction between PLT-specific antibodies and HLA Class I antibodies are evaluated. Each year, serum samples from five patients and four donor blood samples for DNA typing were distributed. Laboratories could participate as a screening laboratory (SL; n = 7) or as an identification laboratory (IL; n = 8). SLs scored 57 to 100 percent correct positive and 91 to 100 percent correct negative results in the detection of PLT-specific antibodies. SLs only using a PLT immunofluorescence test (PIFT) scored less well than those using a PLT glycoprotein-based antibody detection method. ILs scored 70 to 100 percent correct positive and 87 to 100 percent correct negative results for, respectively, the detection and identification of PLT-specific antibodies. Both the specificity and the sensitivity for the detection and identification of PLT-specific antibodies were not as good in ILs using solid-phase enzyme-linked immunosorbent assay methods as in those using the monoclonal antibody immobilization of PLT antigens (MAIPA) assay. For HPA-1, -2, -3, and -5 genotyping, incorrect results were observed only twice in 280 genotyping assays. The data underscore the necessity of using the most accurate methods with a high level of knowledge, experience, and technical training. For screening purposes, it is not sufficient to use only the PIFT, whereas for identification of PLT-specific antibodies, the MAIPA assay is the superior assay.