In vivo effect of delipidified cell component of Mycobacterium leprae in relation to infection with leprosy bacteria in mice.

The delipidified cell component (DCC) of Mycobacterium leprae was used as an immunomodulatory agent in Swiss white mice. The peritoneal macrophages of these mice were activated to produce increased amount of reactive oxygen intermediates like hydrogen peroxide (H2O2) and superoxide. These macrophages also attained the ability to kill M. Leprae in vitro as shown by several assay systems including the conventional mouse foot-pad technique. The increased levels of superoxide seem to be responsible for the killing of M. leprae as addition of the enzyme superoxide dismutase, which breaks down O2, resulted in survival of these bacilli inside the macrophages. The increased production of H2O2 does not seem to be responsible for killing M. leprae. The results indicate that the DCC of M. leprae acts as an effective immunomodulator in mice leading to the activation of macrophages with increased production of H2O2 and superoxide as well as enabling them to kill M. leprae via the action of superoxide anions.