A genetic survey of rat cardiac allograft rejection in presensitized recipients.

A genetic study of cardiac allograft rejection in 24 rat strain combinations sensitized by skin graft immunization has revealed that all grafts are rejected in either accelerated or hyperacute fashion. In the four strain combinations tested, the BN strain responded by rejection in hyperacute manner and the ACI strain was highly immunogenic in four strain combinations. No evidence for genic interaction was revealed by presensitization when the parental L and Bf or LBf F1 strains were studied with WfBN F1 recipients. The Lewis strain, used in many enhancement studies with BN or LBN F1 did not react with hyperacute rejection when immunized with BN. F1 hybrid to F1 hybrid haplotype-matched combinations showed accelerated rejection only. In a segregating backcross population of (L X LACI)F1, hyperactue rejection was associated with disparity at the Ag B (H-1) locus. It is concluded that the rat is a suitable species for studies of hyperacute rejection if the proper strain combination is chosen; strain-specific immune responsiveness, as well as disparity at the major histocompatibility complex and antigen dose, may be a factor in producing the phenomenon.