Coronary atherosclerosis in transplanted mouse hearts. I. Time course and immunogenetic and immunopathological considerations.

An experimental system is described in which coronary arteries of mouse hearts transplanted heterotopically develop obstructive lesions by 4 weeks. Transient immunosuppression permits graft survival. Donor/recipient antigenic differences may be either class I or class II major histocompatibility antigens (H-2) or non-H-2 antigens. An infiltrate including CD4+ and CD8+ T lymphocytes and macrophages concentrates early in the intima and adventitia of larger coronary arteries, with little in the myocardium. Subsequently, the intima expands with cells of donor origin and the infiltrate invades the media. Endothelial and intimal cells express ICAM-1, leukocytes LFA-1: Endothelium expresses class I, but not class II, antigens. As class II disparity alone suffices, the endothelium can apparently be an indirect target of immune injury. We propose that graft atherosclerosis is T cell initiated and elicited by heterogeneous antigens in the endothelium or media. It is separable from rejection of the myocardium.