Candida albicans was studied for its capacity to induce TNF production from mouse peritoneal macrophages (PM Phi). TNF activities in the culture supernatants of candida-stimulated PM Phi and human peripheral blood monocytes were assessed by L 929 bioassay and ELISA respectively. C. albicans induced TNF production from PM Phi and human peripheral blood monocytes in a dose-dependent manner. Although the capacity was lesser than live form, heat-killed C. albicans was also found to be capable of stimulating PM Phi, to induce TNF. The filtered supernatant of 24 h cultured live C. albicans had no effect on TNF production from PM Phi. Saccharomyces cerevisiae-extracted mannan, a yeast cell wall antigen, induced TNF production from PM Phi, in a dose-dependent manner. Thus, the effect of C. albicans on TNF production from PM Phi was seemed to be directly related to the presence of the yeast cell wall itself. Compatible with these data, when various candida species (C. albicans, C. tropicalis, C. pseudotropicalis. C. lusitaniae, C. krusei, C. parapsilosis, C. guilliermondii, C. stellatoidea, C. glabrata) and S. cerevisiae were compared to each other, at a concentration of 2x10(6) yeast cells/ml from each species, it was observed that TNF inducing capacities varied. Among the species used in this study, C, guilliermondii and C. glabrata, of which the yeast cell size were the smallest ones, were found to be less potent than that of others to induce TNF from PM Phi.