IMMUNOLOGICAL STUDIES ON A C POLYSACCHARIDE COMPLEX OF GROUP A STREPTOCOCCI HAVING A DIRECT TOXIC EFFECT ON CONNECTIVE TISSUE

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Abstract
It is demonstrated that antibodies against C polysaccharide can specifically neutralize the capacity of the toxic cellular component of group A streptococci to produce chronic remittent lesions of dermal connective tissue. Rabbits were hyperimmunized with a killed pepsin-treated avirulent strain of a type 3 organism. The unique histological features of the connective tissue lesion were greatly modified in these animals when challenged with an extract derived from a type 1 organism. The antiserum from these rabbits was absorbed with sonic disrupted cells of a strain derived from the immunizing organism but producing an antigenically distinct C polysaccharide. This absorbed serum contained only antibodies against the C polysaccharide as demonstrated by agar diffusion techniques, and specifically precipitated and neutralized the connective tissue toxin. This immune precipitation and neutralization was inhibited by prior absorption of the antiserum with formamide-isolated C polysaccharide or N-acetyl glucosamine. Other studies have shown that C polysaccharide is a poor antigen in man under conditions of natural infection, especially in patients developing late complications. The immunological properties of C polysaccharide and the features of the experimental lesion produced with toxic C polysaccharide complexes indicate that this material should be investigated as a possible factor in the pathogenesis of nonsuppurative sequelae.