Major-histocompatibility-complex-restricted male skin graft rejection responses in rats

Some new perspectives on transplantation immunity and tolerance

To provoke a rejection response, an allograft's antigens must be presented to the host by accessory cells of the graft's MHC genotype. Tolerance induction, too, in neonatal rodents is an MHC-restricted response: third party grafts on tolerant animals survive longer if they are MHC-compatible with the tolerizing cells, rather than the host. In this article, Willys Silvers and his colleagues review the evidence for these observations and discuss their implications.

Major histocompatibility complex (MHC) restriction of foreign transplantation antigens in rats rendered tolerant at birth

Evidence is presented that MHC restriction of foreign transplantation antigens occurs when tolerance is induced. Whereas PVG and F344 rats rendered tolerant at birth with (DA X PVG)F1 and (DA X F344)F1 hybrid bone marrow cells (BMC), respectively, accept ACI skin grafts, presumably because the foreign transplantation antigens of these third party grafts, which are MHC-compatible with DA, are recognized only in association with the MHC of the hosts, DA rats rendered tolerant with (DA X PVG)F1 or (DA X F344)F1 hybrid BMC usually reject ACI skin. Further support that MHC restriction accompanies the induction of tolerance is provided by the observation that Lewis.1N rats rendered tolerant at birth with athymic (nude) Wag BMC are much more likely to accept BN.B2 (MHC-compatible with Wag) skin grafts, than BN (MHC-compatible with Lewis.1N) grafts.

Limitations of a histologic assay for syn-, allo-, and xenogeneic H-Y antigen

In view of the potential significance of the H-Y antigen in the etiology of cases of sexual ambiguity we have attempted to develop a clinically useful test for the presence of H-Y on the cells of such patients. The attempts were directed at the detection of accelerated or decelerated rejection of syngeneic skin grafts on H-Y-incompatible mice previously exposed to H-Y positive syngeneic, allogeneic, or xenogeneic cells. Using a simple and rapid histologic assay after exposure to syn- or allogeneic cells, acceleration (sensitization) as well as deceleration (tolerance) was readily demonstrable. However, the assay was not helpful with the use of xenogeneic (rabbit, human) cells.

Evidence that major histocompatibility complex restriction of foreign transplantation antigens occurs when tolerance is induced in neonatal mice and rats

Studies on the survival of skin-specific antigen (Skn)-incompatible skin grafts in mice rendered tolerant at birth with major histocompatibility complex (MHC)-incompatible lymph node and spleen or bone marrow cells, as well as studies concerned with the survival of third-party skin grafts in rats rendered tolerant at birth with MHC-incompatible bone marrow cells, indicate that MHC restriction of foreign transplantation antigens occurs when tolerance is induced. Thus, evidence is presented that animals rendered tolerant with MHC-incompatible bone marrow cells depleted of mature T lymphocytes will accept any graft that is homozygous for the bone marrow donor's foreign MHC. Evidence has also been obtained that continuous exposure to foreign transplantation antigens in association with an MHC different from that of the graft may induce unresponsiveness to the same antigens in association with the MHC of the graft.