[Cross reactions between polysaccharides of group A, L, and A-variant streptococci]

In group A and A-variant streptococcal antisera the presence of antibodies reacting with group L streptococcal polysaccharide (L polysaccharide) was revealed. Group A and A-variant streptococcal polysccharides (A and V polysaccharides) were shown to be partially identical to L polysccharide by means of the precipitation test in agar gel. Experiments in inhibiting the reactions of the above mentioned antisera with A, V and L polysaccharide preparations suggest the presence of a determinant common to all these polysccharides and differing from the "ramnose" determinant of the polysaccharides and from the determinant characteristic of A polysaccharide. In the identification of group A streptococci by the immunological methods, as well as in the study of cross reactions with the tissues of mammals, the possible presence of antibodies against various antigenic determinants of A polysaccharide, one of which is also common to L polysaccharide, should be taken into consideration.