Relationship of Bacillus Calmette-Guérin-inducedSuppressor C@llsto

Bacillus Calmette-Guërin(BCG) stimulated the proliferation of granulocyte-macrophagecolony-formingcells (CFU) and activated suppressor cells that inhibit the immunization of T lymphocytes in vitro. Increases in both CFU concentration and suppressor cell activity were moderate in the bone marrow and marked in the spleen of mice given BCG i.v. In the bone marrow, these increases were apparent 2 days after treatment with BCG, while in the spleen they did not occur until 7 days after BCG. A BCG strain that produced no increases in CFU concentrationalso producedno activation in suppressorcell activity. Fractionationof spleencells through nylon wool and density gradients revealed that cell populations enriched in CFU were also enriched in suppressor cell activity. The paral lelism in the response of CFU and suppressor cells to BCG indicates that there is a close relationship between these two