[The suppression of delayed hypersensitivity to BCG antigens in BALB/c mice during the production of antibodies to the rhamnose determinants of Streptococcus group A polysaccharide].

The data obtained for the first time in our studies indicate that the production of antibodies to group A streptococcal polysaccharide (A-PS), one of the cross-reacting streptococcal antigens, may suppress delayed hypersensitivity (DH) to microbial antigens. The existence of sharply pronounced correlation between the suppression of DH and the presence of antibodies to the rhamnose area of A-PS in the blood of BALB/c mice immunized with the pepsin-treated culture of group A streptococci has been shown. The suppression of DH is absent in the immunized animals of the same group whose blood contains antibodies to the determinant, specific for A-PS. As revealed in this study, the effect of the suppression of antigen-specific cytotoxicity linked with DH to BCG antigens can be reproduced by mixing lymph node cells taken from these two groups of the animals. The data thus obtained are possibly linked with the activation of nonspecific T suppressors in the production of antibodies to the rhamnose determinants of A-PS in the animals immunized with streptococci. The mechanism of the newly discovered phenomenon is discussed.