Methods for the selection of platelet products for alloimmune-refractory patients

The ability to efficiently and accurately diagnose the cause(s) of platelet (PLT) refractoriness is paramount in providing effective PLT products for transfusion. Recent advances in methods for detecting and identifying alloantibodies against human leukocyte antigens (HLAs) and human PLT antigens, combined with accurate molecular techniques for HLA typing, have provided a framework for the development of clinical algorithms to support such patients. Alloantibodies may be detected and/or identified by several methods, including complement‐dependent cytotoxicity, enzyme‐linked immunosorbent assays (ELISA), and microbead‐based assays using Luminex or flow cytometry. The primary difference in these assays is the sensitivity of detection and the range of antibody specificities that may be reliably identified. Direct PLT cross‐matching to identify compatible PLTs can be accomplished by several methods, including solid‐phase red cell adherence, modified antigen capture ELISA, and flow cytometry. A survey of blood centers and laboratories providing transfusion support has identified the heterogeneity of testing options available, areas of concern and need for improvement, and common obstacles in providing appropriate and timely support to immune‐refractory PLT patients. Depending on the testing methods and the pool of HLA‐typed PLT donors available, there are numerous options for developing suitable algorithms to provide effective support to immune‐refractory PLT patients.