Results of the local graft-versus-host reaction support the immunogenetic concept of the insulin-dependent Diabetes mellitus in BB rats.

The local GVHR was studied by the popliteal lymph node assay in adult randombred BB/DK rats, their parental WOK rats and their interstrain F1 and BC1 hybrids as well as in the LEW triplet of congenic and recombinant strains. A strong GVHR was observed when BB/DK rats were used as recipients. On the contrary, only weak GVHR were found in most cases with BB/DK donors of lymphoid cells. This lowered graft-versus-host reactivity of BB lymphoid cells provided further evidence for a genetically determined defect of the differentiation process of lymphoid cell subpopulations, most probably caused by the mutant RT1u haplotype in BB rats.