Suppression of T-cell responses to histocompatibility antigens by BCG pre-treatment.

The injection of 3 mg BCG into C57Bl/6 mice was followed 14 days later by a decrease in reactivity of spleen cells when engaged in mixed-lymphocyte reactions or in graft-versus-host reactions. In vitro, the lack of reactivity was due to an active suppression exerted mainly by the adherent population. In vivo, it was not possible to demonstrate active suppression.