Studies of antibodies to non type specific antigens associated with streptococcal M protein in the sera of patients with rheumatic fever

Antibodies against the non type specific (NTSM) antigens in purified M protein preparations were found to be widely distributed in human sera but were consistently present, and in highest titer, in the sera of patients with acute rheumatic fever. These NTSM antibodies were measured by CF and passive hemagglutination (PHA) using as antigen purified M30, a serotype now rarely encountered. The sensitization of human blood group O erythrocytes for the PHA test afforded the opportunity to identify antigens in M protein preparations that have, like teichoic acid, an affinity for red cell membranes. Red blood cells were sensitized with M protein and with teichoic acid, respectively, and were compared as absorbents of serum NTSM antibodies. PHA antibodies were removed in reciprocal fashion by both sensitized erythrocyte preparations suggesting that the absorbed M protein contains teichoic acid. Either teichoic acid or M protein sensitized erythrocytes absorbed only a portion of the CF antibodies to M30 protein present in rheumatic fever sera. In contrast streptococcal protoplast membranes absorbed virtually all of the CF antibody. These results show that purified M proteins of group A streptococci contain at least two NTSM antigens which are also present in streptococcal protoplast membranes and to which rheumatic fever patients are hyperimmune. One of these is teichoic acid or a closely related antigen.