Comparison of the bead-based simultaneous analysis of specific platelet antibodies assay (SASPA) and Pak Lx Luminex technology with the monoclonal antibody immobilization of platelet antigens assay (MAIPA) to detect platelet alloantibodies.

Background: The identification of platelet alloantibodies is indispensible for the diagnoses of fetal/neonatal alloimmune thrombocytopenia and refractoriness to platelet transfusions.
Methods: We compared the results obtained with the gold-standard assay for the detection and specification of platelet antibodies, the monoclonal antibody-specific immobilization of platelet antigen assay (MAIPA), with those from two bead-based assays, simultaneous analysis of specific platelet antibodies assay (SASPA), and the recently commercialized bead-based assay Pak Lx.
Results: For the detection of alloantibodies by SASPA, the sensitivity was 94.6%, the specificity was 99.5% The respective results for Pak Lx were 98% and 99.8%. Some antibody specificities were revealed by SASPA or Pak Lx but not by MAIPA. However, there were also antibodies detected by MAIPA that were not seen by SASPA or Pak Lx. Antibody dilution experiments suggest that SASPA or Pak Lx are more sensitive than MAIPA.
Conclusions: All three assays have limitations, but Pak Lx is suited for screening. However, other assays are necessary if results are not conclusive or for evaluations beyond the commercial assay's design.