Enhancement of resistance in Mycobacterium lepraemurium infected C3H mice by treatment with sonicated M. lepraemurium or splenectomy.

C3H mice were first infected in a hind footpad with 10(7) freshly harvested Mycobacterium lepraemurium bacilli. Four weeks later, when a granulomatous reaction was detected at the inoculation site, the animals were treated with two doses of a whole sonicated preparation of M. lepraemurium administered 2 weeks apart in the contralateral footpad. Such treatment was found to prolong the survival time of infected mice by 55-60 days. To study the involvement of the spleen in the immunomodulation of resistance to M. lepraemurium infection, splenectomy was performed in mice prior to infection via two different routes. Splenectomy significantly prolonged the mean survival time of mice infected in the footpad but did not affect survival of those infected intraperitoneally. Treatment of splenectomized footpad infected mice with sonicated bacilli abrogated almost completely the beneficial effect of splenectomy.