Report on the 14th International Society of Blood Transfusion Platelet Immunology Workshop

The aims of the 14th ISBT Platelet Immunology Workshop were to evaluate in-house methods for detection of antibodies to human platelet antigens, to compare the sensitivity and specificity of antibody detection using a panel of monoclonal antibodies and to evaluate genotyping methods and establish procedures for drug-dependent antibody detection.

Forty-two laboratories from 23 countries participated. Samples and reagents provided for the five different exercises.

The ability of participating laboratories to correctly identify the HPA antibody specificity in the nine samples ranged from 20% to 97%. The greatest difficulty was observed with samples that contained antibodies against HPA-3b and GPIV. The significant differences in optical density values by monoclonal antibody of immobilization of platelet antigens (MAIPA) assay were observed when testing the same platelet-specific antibodies. HPA genotyping of DNA with novel mutations did not significantly affect the results. The overall average discrepancy rate was 2·15% for genotyping of 10 DNA samples from well-characterized Epstein–Barr virus transformed cell lines. For detection of drug-dependent antibodies, excellent results for specificity and sensitivity were obtained by the laboratories using the MAIPA and flow cytometry.

Most laboratories were able to identify the majority of HPA antibodies; however, significant disparities were observed in proficiency testing. MAIPA assay sensitivity is influenced by the monoclonal antibody clone used. DNA with new mutations and EBV cell lines are valuable samples to ensure accurate genotyping. A sensitive and specific drug-dependent antibody assay performed well in the hands of participants.