Acceptance of H-Y-disparate corneal grafts despite concomitant immunization of the recipient

Male-specific, H- Y antigen is a widely utilized antigen system for analyzing the role of non-MHC transplantation antigens in graft rejection. In this study, we examined the role of H-Y antigen in corneal graft rejection. Orthotopic corneal grafts from male LBNF₁ rats were transplanted to syngeneic female LBNF₁ recipients. The male corneal grafts survived beyond 100 days on naive female recipients. In other experiments, hosts bearing clear male corneal grafts and systemically immunized with subcutaneous inoculations of male splenocytes followed by full-thickness male skin grafts failed to reject their corneal grafts, even though the male skin grafts were swiftly rejected. The inability of female hosts to reject existing male corneal grafts suggested that the cornea failed to express H-Y transplantation antigen. Further experiments, however, revealed that male-specific antigen was expressed on corneal grafts. Hosts bearing clear male grafts in the left eye rejected subsequent male skin grafts and promptly rejected male corneal grafts transplanted to the contralateral eye. Interestingly, the original male corneal grafts remained clear during the rejection of both the skin graft and the second corneal graft. The results indicate that corneal grafts representing minor histocompatibility disparities enjoy immunologic privilege in the naive host, even if the host is subsequently immunized systemically.