Detection of heart-reactive antibody in Balb/c mice immunized with Streptococcus mutans

Abstract

Heart-reactive antibodies were examined by ELISA, in sera from 14 Balb/c mice immunized with Streptococcus mutans inactivated by treatment with formaldehyde. Anti-heart and anti-myosin IgG levels increased significantly in the sera from immunized mice, when compared with those of control sera, especially in the first group, inoculated with a new antigen preparation. This group displayed a notable reactivity with cardiac myosin and cardiac tissue proteins in Western-blotting, mainly with a 35 kDa peptide. The histological analysis of immunized animals’ cardiac tissue demonstrated the existence of cell injury and eosinophilia attributable to cellular hyaline change. The pericardium and the myocardium showed inflammatory infiltrate formed by lymphocytes and macrophages. These findings suggest the existence of molecular mimicry between S. mutans and the cardiac tissue and emphasize the risk of development of an autoimmune myocarditis induced by caries vaccine containing streptococcal fractions.