Epitope-based matching for HLA-alloimmunized platelet refractoriness in patients with hematologic diseases

For HLA-alloimmunized patients, platelet (PLT) concentrations are provided either at matched HLA-A and HLA-B loci or by serologic cross-reactivity groups (CREG) matching strategy. However, this method has some limitations.

In this study, the epitope-based matching (EBM) method was evaluated for selecting proper HLA-typed PLTs for patients with PLT transfusion refractoriness. Bead-based single-antigen HLA antibody detection method and HLAMatchmaker software were used to define the epitopes recognized by HLA-specific antibodies and to select compatible PLTs for nine patients with alloimmunized refractoriness. Corrected count increments (CCIs) were prospectively determined to compare successful transfusion rates among different matching methods in 142 PLT transfusions. In addition, HLA antibodies were serially detected to see whether any emerging antibodies appeared after receiving the EBM-matched PLTs.

The transfusion success rates evaluated with 1-hour CCIs for perfect matching or lacking any mismatching at HLA-A and -B locus (A/BU)-matched, CREG-matched, and EBM-matched PLTs were 85.2, 63.2, and 83.7%, respectively. Compared to CREG-matched PLTs, EBM-matched PLTs showed better transfusion results (p = 0.035). In the follow-up study (7 months; range, 3-13 months), no emerging HLA-specific antibodies were detected after receiving EBM-matched PLTs.

EBM performed on the basis of bead-based single-antigen HLA antibody detection coupled with the HLAMatchmaker program is recommended in choosing proper PLTs for refractory patients when A/BU-matched PLTs were not available.