Transfusion-associated graft-versus-host disease (TA-GVHD) was described as occurring after nonirradiated blood tranfusion not only in immunosuppressed but also in immunocompetent recipients who share one HLA haplotype with HLA-homozygous blood donors.
From the distribution of 1% or more frequencies of HLA-A, -B, -C, -DR, -DQ haplotypes obtained at the 11th International Histocompatibility Workshop (1991), using the fomulae of Kanter, we tried to calculate the potential risk of TA-GVHD as a result of directed donations from relatives in the Japanese and other ethnic groups.
The Japanese have the greatest risk of TA-GVHD than any other populations because are more homogeneous in HLA and have a common haplotype: A24-CBL-Bw52-DRw15-DQw1 (7.5%).
Of noteworthing, the risk of transfusion of HLA-homozygotes to heterozygotes among 1st-degree relatives in the Japanese was 4.7-folds compared with that of transfusion in the U. S. A. population. And, the risk of TA-GVHD among the Japanese unrelated was near to that of transufusion among the French first degree relatives.
Therefore, we recommend that donations of blood components from recipient's relatives should be irradiated essentially, and as possible even from unrelated donors in the Japanese population.
