Strain difference in rats with experimental giant cell myocarditis.

Immunogenetic mechanisms may be involved in the pathogenesis of myocarditis and dilated cardiomyopathy. The present study investigated the incidence, histopathology and histocompatibility characteristics of experimental giant cell myocarditis in various strains of rats. Experimental giant cell myocarditis was induced by immunization with porcine cardiac myosin in Lewis (RT-1(l)), Dahl (DIR/Eis) (RT-1(l)), Fisher (RT-1(lv 1)) rats, but not in Dahl (DIS/Eis) (RT-1(l)) or Brown Norway (RT-1(n)). Myocarditis was most severe in the Lewis rats and their heart weight/body weight ratio was significantly higher than that of control rats immunized with Freund's complete adjuvant alone. In conclusion, this study provides evidence that the expression and severity of experimental giant cell myocarditis may be determined mainly by genetic factors, including both major histocompatibility complex genes as well as other genes, which may be controlled by an immune mechanism.