T cells in cardiac myosin-induced myocarditis

Autoimmune myocarditis induced by immunization with cardiac myosin can be seen as a virus-free system to analyze the immunopathological mechanisms of certain forms of postinfectious heart disease. Immunodepletion studies have shown that in A.SW mice myosin-induced myocarditis is mediated by both CD4+ and CD8+ cells. The CD4+ subset is at least required for the induction of the autoimmune response, whereas the CD8+ subset seems to play a key role in mediating the myocardial injury. In addition, we found a bias concerning the TCR repertoire, because T cells within the inflammatory heart infiltrate almost exclusively use V beta 8 elements. Furthermore, recent serologic and immunohistologic studies indirectly suggest that the cardiac myocyte is not the target for the anti-myosin response. Rather, the primary target might consist in dendritic cells presenting myosin epitopes even under normal conditions.