[Analysis of anti-platelet antibodies using flow cytometry]

We analyzed the production of anti-platelet antibodies by alloimmunization in patients with hematological disorders who receive blood transfusions frequently. HLA antibodies were detected by anti-human globulin lymphocyte cytotoxicity test (AHG-LCT), and anti-platelet antibodies by flow cytometry (FCM). Results from FCM correlated well with those of AHG-LCT. The rate of coincidence was 92.1%. Production of alloantibodies in patients was detected in 32.7% in the without filter group, but decreased to 17.1% (p < 0.05) in the filter group. The avidin-biotin assay and concentration of globulin fraction in patient's serum by affi-gel blue column were useful for increasing sensitivity in detecting anti-platelet antibodies. Anti-platelet specific antibodies were detected in 5 patients (5/226; 2.2%) and these antibodies coexisted with HLA antibodies in all patients. The antibody in 3 of these patients were identified as HPA-2b (Siba), and those in the other 2 patients were combined antibodies on platelet identification panel and immunoblotting. It may be possible that high titer serum of anti-platelet specific antibodies could be identified by its fluorescent intensity. Measures against HPA-2b are considered necessary because platelet specific antibodies were produced in 2.2% of patients who received blood transfusions frequently.