Slot blotting and flow cytometry: two efficient assays for platelet antibody screening among patients with platelet refractoriness

Background and Objectives Frequent platelet transfusion may lead to the formation of alloantibodies and immune‐mediated platelet destruction. Currently, identifying economic and effective screening methods is necessary for the management of platelet transfusion while different tests were recommended. The present study aims to challenge the performance of slot blotting (SB) and flow cytometry (FC) assays in detecting immune platelet refractoriness. Materials and Methods Sera from 118 patients who received blood components and were clinically suspected of platelet refractoriness were enrolled. Platelet‐reactive antibodies were explored in parallel by SB, FC and monoclonal antibody‐specific immobilization of platelet antigens (MAIPA) techniques. In a further study, chloroquine‐treated platelets were incubated with MAIPA‐positive serum, and then, the results of the SB and FC techniques were compared. Results Using MAIPA as a reference, antibodies were detected in 51 sera, with specificity for human leucocyte antigens (HLA), human platelet antigens (HPA) or both HLA/HPA, in 27, 18 and 6 patients, respectively. The sensitivity and specificity of SB and FC were 86·3%, 88·1%, 82·4% and 95·5%, respectively. The Spearman correlation revealed significant ( P < 0·001) correlations between FC ( r = 0·763) and SB ( r = 0·738) with MAIPA. In respect to HPA antibody detection, SB had 83·3% sensitivity and 92·6% specificity compared to 91·7% and 96·3% for FC while both approaches are acceptable ( P < 0·001, r = 0·69; P < 0·001, r = 0·773) and can be recommended. Conclusions The present study acknowledges that among the used methods, the flow cytometry's performance is the most appropriate, but slot blotting, with acceptable sensitivity, can be used as an acceptable and convenient procedure for platelet antibody screening.