IN-VIVO PROTECTIVE EFFECT OF THE LECTIN FROM CANAVALIA-BRASILIENSIS ON BALB C MICE INFECTED BY LEISHMANIA-AMAZONENSIS/

In vivo administration of Canavalia brasiliensis lectin (at the time o f infection, or maintained throughout the infection) reduced the lesio ns of highly susceptible BALB/c mice infected by Leishmania amazonensi s. At the doses used C. brasiliensis lectin (ConBr) does not interfere with penetration or fate of Leishmania in the macrophages in vitro. S ince Interferon-gamma (IFN-gamma) is the major macrophage activating f actor, and considered a critical. element in the successful immune res ponse against leishmaniasis, we explored its participation in this phe nomenon. ConBr either in vivo or in vitro induced IFN-gamma production in normal or in leishmania-infected BALB/c mice. However we were unab le to change the course of disease by in vivo IFN-gamma administration (although IFN-gamma preparations were effective in inducing a leishma nicidal effect in vitro on L. amazonensis-infected peritoneal macropha ges). Additionally, IFN-gamma neutralization with anti-IFN gamma monoc lonal antibody did not alter the protection conferred by ConBr adminis tration. These data show that lectin administration in vivo is protect ive in the otherwise unchecked L. aniazonensis infection of BALB/c mic e, and suggest that such effect is not mediated by IFN-gamma.