HLA class I monomorphic monoclonal antibody Yu-3-20A, HLA class II monomorphic monoclonal antibody TOK39-4, and HLA-A and -B interlocus monoclonal antibody TOK45-3A were used in the ELISA assay of platelets. We used 9 samples from the A24-negative and Bw4-negative, 15 samples from the A24-positive, 10 samples from the Bw4-positive, and 18 samples from the A24-positive and Bw4-positive individuals. The monoclonal antibody Yu-3-20A showed the identical positive reactivity with all of the platelets used. The monoclonal antibody TOK39-4 showed no reactivity with any of the platelets. The monoclonal antibody TOK45-3A showed positive reaction with an O. D. value of 0.741±0.271 with 25 samples of the platelets possessing either A24 or Bw4. It also showed reaction with an O. D. value of 1.535±0.253 with the platelets possessing both of the A24 and Bw4. This results indicate that the reactivity with HLA-A and -B interlocus monoclonal antibody correlates with the HLA phenotype of platelets.
