Report on the Tenth International Platelet Genotyping and Serology Workshop on behalf of the International Society of Blood Transfusion

Background and Objectives The aims of the 10th International Platelet Serol ogy and Genotyping Workshop were to evaluate the proficiency of platelet im munology determinations. Materials and Methods There were 40 participants from 25 countries of four continents. Thirty-eight institutions reported results for genotyping, and 38 institutions reported their serological results. For genotyping, EDTA-an ticoagulated whole-blood samples were provided (to allow the inclusion of D NA-separation methodology in the analysis) as well as separated DNA. of a a nd b alleles for human platelet antigen (HPA)-1 to -6. For serological eval uations, sera contained allo- and autoantibodies, and for sensitivity testi ng a standard freeze-dried sample of HPA-5 antibody. Results All participants reported HPA-1, -2, -3 and -5 genotyping results; HPA-4 was determined in 29 laboratories and HPA-6 in 21. Results from 16 la boratories were concordant with the majority vote for all allotypes, eight institutions reported one deviation, five laboratories two, and nine labora tories three or more deviations. Twelve institutions had no deviation from the majority vote for HPA antibodies, nine had one, three had two, and 14 h ad three or more deviations. Most laboratories reported a reactivity of the standard anti-HPA-5b sample with HPA-5b platelets at a dilution of 1 : 4-1 : 8. Four laboratories detected anti-Gov(a) in one sample. Seventeen labor atories reported no deviation from the majority vote for pan-reactive plate let antibodies, 12 had one deviation, two had two, and seven had three or m ore deviations. In addition, seven participants reported antibodies against glycoprotein IV (GPIV), three against glycoprotein V (GPV) and three again st CD109. These results were discussed at a meeting organized jointly with the International Society of Blood Transfusion (ISBT) 2000 Congress. Conclusion The results for pan-reactive antibodies were heterogeneous with most discrepancies from the majority vote. The provision of sufficient samp les for many participants is difficult. Based on the results and discussion it is clear that frequent workshops are needed in the future. Therefore, w orkshops shall be organized regionally, and each region shall participate w ith one institution in international workshops. The latter are needed to as sure international exchange of experience and quality.