[Study of cross reactions between group A streptococcal antigens and cardiac interstitial connective tissue fibroblasts of different species of mammals].

It has been revealed by indirect immunofluorescence that sera of rabbits immunized with group A streptococcal non-type-specific antigens and F (ab')2 fragments of IgG obtained from these sera intensively react with fibroblasts of interstitial connective tissue (ICT) of the myocardium of humans and different mammalian species with the exception of rabbits. Negative or weak reactions with the same sera and F (ab')2 fragments were observed with fibroblasts of ICT of nonimmunized rabbits. Myocardial ICT of immunized animals showed bound immunoglobulins. This model can be used for making clear the reason for presence in sera of rheumatic patients circulating antibodies only to heterologous but not to homologous ICT of the myocardium regardless of the revealing bound immunoglobulins in the ICT of these patients.