Dissociation between cell-mediated immunity and acquired resistance in systemic murine candidiasis

Mice immunized with 10(7) heat-killed (HK) Candida albicans injected subcutaneously with or without BCG, used as an immunoadjuvant, were able to develop strong significant delayed-type hypersensitivity (DTH) against C. albicans but without any increase in specific resistance, as measured by median survival time and enumeration of yeasts inside target organ such as lungs, liver, spleen and kidneys after an intravenous (i. v.) challenge of 1 X 10(6) live C. albicans. Concomitant activation of the mononuclear phagocytic system, measured in vivo by increased resistance to L. monocytogenes, was shown to be induced in immune mice challenged i. v. with 1 X 10(6) HK C. albicans. These results are in favour of a clear distinction between DTH and acquired resistance to systemic candidiasis, even in the presence of specific activation of macrophages.