Streptococcal cross-reacting antigen and the bundle of His.

Five sera raised in rabbits against three strains of Streptococcus pyogenes (grown in semi-synthetic media) were shown by immunofluorescence to have antibodies reacting with both myocardial and conducting fibres. The pattern of staining on the conducting fibres was different to that on myocardial fibres and suggested the presence of larger amounts of cross-reacting antigen. Most work was done on ox heart, but the results were confirmed on human heart and rabbit heart. Absorption studies, carried out with three sera on ox heart only, showed that absorption with the homologous organism abolished in parallel the staining of both types of fibre. Absorption with heterologous organisms was less effective indicating the existence of more than one cardiac cross-reacting antigen. Absorption with myocardium, suggested that the conducting fibres contained streptococcal cross-reacting antigens additional to those found in the contractile fibres.