The presence of HLA-homozygous typed cell (HTC) in transfused blood cells possibly induces transfusion-associated graft versus host disease (GVHD) which usually causes immediate death for transfusion-associated GVDH in a Japanese population, the frequency of HTC was investigated by serological typing for class I antigens and by DNA typing for class II antigens. Out of 3, 000 Japanese cells randomly collected, cells from 32 Japanese (1.1%) were found to be HLA-homozygous for the HLA-A, -B, -C, DRB1, DQA1 and DQB1 genes. This high frequency suggests that removal or inactivation of leukocytes in donors' blood is necessary to prevent transfusion-associated GVHD.
