[Anti-platelet antibody by alloimmunization after frequent blood transfusion in patients with hematological...

We analyzed the production of anti-platelet antibodies by alloimmunization and examined the prevention of alloimmunization in patients with hematological disorders who have received blood transfusion frequently. HLA antibodies were detected by anti-human globulin lymphocyte cytotoxicity test (AHG-LCT), and anti-platelet antibodies by flow cytometry and mixed passive hemagglutination test (MPHA). A leukocyte removal filter was used for preventing production of alloantibodies. The leukocytes in blood derivatives were removed over 99% by use of this filter. Production of HLA antibodies was detected in 32.7% in control group, but was decreased to 17.1% (p < 0.025) in the filter group. Anti-platelet specific antibodies were detected in 5 patients (5/226; 2.2%) and these antibodies existed together with HLA antibodies in all such patients. The antibodies in the 3 patients out of them were identified as HPA-2b (Siba), and those in the other 2 patients were considered to be combined antibodies by means of platelet identification panel and immunoblotting. Thus, the leukocyte removal filter was found useful for preventing production of HLA antibodies, and measures against HPA-2b are considered necessary because platelet specific antibodies were produced in 2.2% of patients who received blood transfusion frequently.