Immunosuppression by peritoneal BCG-induced granulomas in mice

1. Intraperitoneal injection of viable BCG resulted in the formation of peritoneal granulomas in mice. Granuloma-bearing animals presented a specific immunosuppression of delayed-type hypersensitivity (DTH) to BCG. 2. The transplantation of peritoneal granulomas induced by BCG to animals previously sensitized with BCG suppressed the DTH response to this antigen in the recipient animals to the same extent as observed in animals with granulomas induced by the injection of BCG. No suppression was observed in animals transplanted with granulomas induced by either Cytodex or talc. 3. The hypersensitivity reaction to Brucella abortus and the acute inflammatory reaction produced by carrageenin were not affected by granuloma transplantation. 4. Granulomas collected from animals treated with a lethal does of irradiation maintained the capacity to suppress DTH in recipient animals. 5. These results suggest that the response observed in granuloma recipients is modulated by cells within the granuloma.