Selectivity in the effects of indomethacin on BCG-activated suppressor cell populations.

Intravenous inoculation of BCG into C57 B1/6 mice activated natural suppressor cells in the bone marrow and induced suppressor cells in the spleen. The suppressor activity of these cell populations was determined by co-cultivating them with normal lymphocytes being immunized against allogeneic P815 cells in vitro. Six million cells from the spleen or bone marrow of BCG treated mice inhibited by more than 50% the alloimmunization of twenty million normal syngeneic lymphocytes. The suppressor cells were found in the nylon wool adherent population in spleen and in both the nylon wool adherent and non-adherent populations in bone marrow. Indomethacin, at a concentration of 10(-6)M, completely blocked the suppression generated by unfractionated spleen or adherent spleen from BCG treated mice. However, 10(-6)M and higher concentrations of indomethacin only partially blocked the suppression generated by unfractionated marrow or adherent marrow from BCG treated mice. The suppression generated by non-adherent marrow from BCG treated mice was completely insensitive to indomethacin.