Studies on the antigen in beta-haemolytic streptococci that cross-reacts with an antigen in human myocardium.

A common antigen has been demonstrated in several serological types of Group A β-haemolytic streptococci. This antigen is cross-reactive with a cardiac and a voluntary muscle tissue antigen in man, the rabbit and the guinea-pig. The streptococcal antigen is present in smooth and matt variants of Group A streptococci, is absent from a type 24 Group A matt streptococcus, is present in Group G and absent from Groups C and D. It is distinguishable from the M type-specific antigen of Group A. The properties of the streptococcal and the cross-reacting tissue antigen have been studied. They are probably complex antigens of protein, polysaccharide and lipid. A similar antigen (or hapten), also cross-reacting with cardiac and voluntary muscle, has been found in human saliva. The salivary and the streptococcal antigens are probably related to the blood group substances. The salivary antigen (or hapten) could be successfully coated upon living streptococci but not upon a living .