Viral myocarditis: immunopathogenesis and the effect of immunosuppressive treatment in a murine model.

Serial changes in lymphocyte subset were investigated in an animal model of encephalomyocarditis (EMC) virus myocarditis in mice. The lymphocyte subset in the peripheral blood was measured by flow cytometry and, T cell subset in the myocardium was stained by labeled avidin-biotin technique. Helper-inducer T cells (Lyt 1 cells) decreased significantly on day 7, but there was no change in cytotoxic-suppressor T cells in the peripheral blood. During the acute stage a significant number of T cells (Thy 1.2 cells) were seen in the heart with helper-inducer T cells predominating. The effect of prednisolone and cyclosporine on viral myocarditis was studied in our experimental model. Prednisolone or cyclosporine given in the early stage aggravated the course, and they did not have beneficial effects during the early recovery period.