Immunohistological analyses of myocardial infiltrating cells in various animal models of myocarditis

Animal models of myocarditis are of great value for studying the pathophysiology of the disease. To clarify the key factors for determining the severity of myocarditis, we analyzed immunohistological surface markers of myocardial infiltrating cells in various animal models, and the relationship between myocardiogenic antigens and abnormal behaviours of infiltrating cells was discussed. Myocarditis was induced in mice and rats by cardiotropic viruses and by porcine cardiac myosin. Animals were sacrificed at the peak of their disease. Pathological examinations were performed, and the severity of the lesions was scored semiquantitatively. There were striking differences in the severity of viral and autoimmune giant cell myocarditis among different animal models. However, the majority of myocardial infiltrating cells were comprised of macrophages and CD4+ T cells. Different immunological behaviours of myocardial infiltrating cells were demonstrated in these models of myocarditis. However, the development of severe myocardial lesions may depend on the macrophage-CD4 cell lineage in these animal models.