Specific immunization of mice against Leishmania mexicana amazonensis using solubilized promastigotes

In this work, it was demonstrated that mice (BALB/c strain) highly susceptible to Leishmania mexicana amazonensis can be protected against infection by this parasite by being preimmunized with whole solubilized (in a buffer that contained EDTA, NP-40, and SDS) promastigotes; the use of adjuvant or intact inactivated parasite cells is shown to be not necessary. The best immunization schedule consisted of three intravenous injections of 5 x 10 to the 7th parasite equivalents, administered one to eight weeks before infection. Immunized mice exhibited a marked inhibition of primary lesion development, reduced numbers of parasites in the spleen, and reduced death rate.