Immunosuppression of anti-sheep erythrocyte responses by glycerol teichoic acid immune complexes.

Sprague-Dawley rats which produce "naturally occurring" antibodies to glycerol teichoic acid (GTA) displayed immunosuppression of anti-sheep erythrocyte plaque-forming cell and serum antibody responses when a single dose of lipid-free GTA was administered 24 h before immunization. Such suppression was enhanced by administering GTA complexed with anti-GTA immunoglobulin G. Animals fed a GTA-free diet produced no anti-GTA immunoglobulins and failed to show GTA-mediated immunosuppression under similar experimental conditions. However, when those animals were given GTA-anti-GTA complexes, suppression was evident. The results suggested antigenic competition mediated by immune complex-activated suppressor T cells. Lipid-free GTA did not stimulate serum antibody responses under the experimental conditions employed.