DISCUSSION
The existence of an immunological relationship between the hemolytic streptococcus
and mammalian tissue is now well established. In the studies reported
here, anfisera to Group A and A variant streptococci from a wide variety of
serological types were shown to contain an antibody which reacted with heart
muscle. Not only did the cardiac myofibers stain with the fluorescein-labeled
streptococcal antibody, but smooth muscle present in the endocardium and in
the media of arterioles also reacted. Although intense staining was observed in
the region of the sarcolemma, exact localization of the antibody-binding site
within the muscle cell was not possible.