Restriction specificity of virus-specific cytotoxic T cells from thymectomised irradiated bone marrow chimeras reconstituted with thymus grafts.

Adult-thymectomised lethally mice A that were reconstituted with T-cell-depleted bone marrow cells of (A X B)F1 origin plus fetal thymus grafts of (B X C)F1 origin generated virus-specific T cells restricted to B alone; adult-thymectomised and lethally irradiated (A X B)F1 mice that were reconstituted with T-cell-depleted bone marrow cells of (A X B)F1 origin plus fetal thymus grafts of A and of B origin generated virus-specific T cells restricted to A or to B. These results do not reveal obvious suppressive influences of host or stem-cell origin that might have explained results obtained with various irradiated bone marrow or thymus chimeras, they indicate that the thymus' influence on maturing T cells is one of the limiting steps in the selection of T cells' restriction specificities.