FACTORS AFFECTING THE ACCEPTANCE OF DEOXYGUANOSINE-TREATED THYMUS ALLOGRAFTS1

dGuo-treated mouse embryo thymus lobes depleted of lymphoid and dendritic cells are not rejected by normal allogeneic mice despite expression of class II major histocompatibility (MHC) antigens on thymic epithelial cells. Our results suggest that host mice are not tolerant to donor antigens, but treated lobes survive because thymic epithelial cells are not immunogenic. Multiple grafts of dGuo-treated lobes are not immunogenic. Mulitiple grafts of dGuo-treated lobes are rejected perhaps because numbers of residual dendritic cells reach a threshold necessary for priming.Mice previously primed by injection of spleen cells reject dGuo-treated thymus lobes, and crossreactions between major and minor histocompatibility antigens can be demonstrated. The acceptance of dGuo-treated thymus allografts by normal mice provides a system for investigating the requirements for priming.