Human leukocyte antigen antibody detection technologies in platelet transfusion refractoriness, with special emphasis on functional test
In the clinical settings of transfusion medicine, human leukocyte antigen (HLA) antibody detection and platelet cross-matching are important tests applied in the management of patients with platelet transfusion refractoriness (PTR). Presently, fluorescence beads technologies using extracted and purified HLA antigens are applied for the HLA antibody screening, and highly sensitive methods such as flow cytometry crossmatch (FCXM) and immunocomplex capture fluorescence analysis (ICFA), based on the use of live intact cells, are used for the cross-matching. Such highly sensitive methods have importantly contributed for the prevention of refractoriness caused by low titer antibodies but, on the other hand, they also detect those low titer antibodies or naturally occurring antibodies without or with unknown clinical relevance. Moreover, the use of recombinant antigens has been shown to be associated with specific issues. In addition, although the relationship between the antibody features and the clinical implications, such as the relevance of antibody subclass in platelet clearance, has been investigated in the field of transplantation, presently, few evidence exists in the literature related to blood transfusion. Here, we reviewed on the available HLA antibody detection methods, the issues of the present methods, and present a new method for the evaluation of clinically significant HLA antibodies using in vitro platelet phagocytosis assay.