Study of a human minor alloantigen in relation to clinical graft-versus-host disease

Sixty-seven pairs of HLA matched siblings, each comprising marrow donor and recipient in the Seattle marrow transplant program, were analyzed to establish phenotype for a newly described minor H antigen, W1. The test for phenotype entailed cold target inhibition of cytotoxicity, directed at this antigen and mediated by specifically stimulated T cell lines. There were 58 compatible and six W1 incompatible pairs. The low frequency of W1 mismatch is due to the strong preponderance of W1-positive individuals in the general population. Severe graft-versus-host disease (GVHD), both acute and chronic, was observed among the 58 recipients of marrow from W1 matched donors. These results do not reveal any particular importance for W1 incompatibility in human GVHD and indeed indicate that other systems are involved. Even if some cases are triggered by incompatibility at W1, the maximum frequency with which this could occur would be about 10%, due to the limited polymorphism of this alloantigenic system.