Effects of passive enhancement on graft and host. Graft adaptation by alloantibody as the mechanism of prolonged skin allograft survival.

The cellular response to passively enhanced allogeneic skin grafts in mice was investigated using alloantiserum raised in hyperimmunized (C57BL/6 X A/J)F1 (B6AF1) against B10.D2oSn (B10.D2) mice. B6AF1 mice given B10.D2 skin grafts and passively enhanced with B6AF1 anti-B10.D2 alloantiserum (anti-31) showed delayed development of the ability to generate high levels of specific cytotoxicity in vitro. This delayed responsiveness was not transferable in vivo to freshly skin grafted mice, nor could cell-mediated suppression of development of in vitro responses be demonstrated in mixing experiments. These results suggested that alloantiserum acted on the graft. When skin grafts from passively enhanced animals were transferred to naive recipients prolonged graft survival was seen. Our results suggest that the mechanism of prolonged graft survival of the passively enhanced murine skin graft was through alteration of inherent graft immunogenicity, rather than a direct effect on the host.