Induction of unresponsiveness to skin allografts in adult mice disparate at defined regions of the H-2 complex. I. Effect of donor-specific bone marrow in ALS-treated mice.

The induction of unresponsiveness to skin allografts was studied in adult congenic B10 mice disparate either at isolated K, I, or D regions of the H-2 complex or at combined K/D and I regions. Recipient mice were treated with antilymphocyte serum (ALS) and injected with donor bone marrow after skin grafting. Unresponsiveness to antigens of the isolated K or D regions (class I) could not be induced, as shown by the inability of bone marrow to prolong graft survival in these mice compared with ALS-treated controls. Significant unresponsiveness to antigens of the isolated I region could be induced by ALS immunosuppression alone, and it was not possible to determine the additive effects of bone marrow. Unresponsiveness to antigens of the K or D regions, or both, could be induced when they were presented with antigens of the I region. This indicates that the I region exerts a tolerogenic effect on the K and D regions. The requirement for the concomitant presentation of antigens of the K/D and I regions to achieve unresponsiveness is consistent with our previous observations that active suppression is one of the mechanisms of the induction of unresponsiveness in ALS-treated, marrow injected mice.