Some Properties of suppressor macrophages induced with Mycobacterium leprae vaccine in mice

Splenic macrophages induced by intravenous injection of Mycobacterium leprae vaccine (ML-vaccine) consisting of heat-killed M. leprae (HK-ML; 6 x 10(8)/ml) and live M. bovis BCG (10 mg/ml) were studied for their suppressive activity against lymphoproliferative response to concanavalin A (Con A). Spleen cells (SPCs) of host mice received 0.1 ml of the vaccine 2 weeks before harvest showed markedly reduced Con A mitogenic response. Such phenomenon was seen also in the case of mice which were given live BCG (1 mg) alone, but was not in the case of injection with HK-ML (6 X 10(7) alone. When splenic macrophages which were cultivated on a microtiter well for a monolayer culture was studied for the suppressive activity against Con A mitogenic response to splenic T cells, potent suppressive activity was found in mice treated with ML-vaccine as well as live BCG alone, but not in mice given HK-ML alone. Activity of the suppressor macrophages per spleen in ML-vaccine-treated mice was nearly the same as in mice given BCG alone. However, the suppressor activity per individual macrophage was considerably higher in ML-vaccine-treated mice than in the case of BCG-injected mice. The two macrophages produced almost the same intensity of chemiluminescence in response to triggering by phorbol myristate acetate, and thereby, indicating that they were activated in a similar level. When resident peritoneal macrophages with a weak suppressive activity against lymphoproliferative response were incubated in the presence of ML-vaccine, their suppressor activities were markedly augmented.(ABSTRACT TRUNCATED AT 250 WORDS)