Role of Candida albicans in granulomatous tissue reactions. I. In vitro degradation of C. albicans and immunospecificity of split products.

Several mannan-containing fractions were obtained from whole cells, cell walls, and cytoplasm of Candida albicans by means of treatment with hot formamide or precipitation with (NH4)2SO4. The immunological and chemical characteristics of the fractions were compared with those of C. albicans mannan prepared by standard procedures. Antisera to C. albicans from rabbits immunized with whole cells of the organism were found to be primarily directed against the mannan content. With use of such antisera, mannan was localized in both the inner and outer layers of the cell wall, whereas the middle layer was found in all likelihood to represent the glucan polymer. Stepwise removal of mannan from whole cells or cell walls resulted in increasing loss of periodic acid-Schiff staining, immunofluorescence, and peroxidase reactivity. Thus, it appears that mannan is responsible for the ability of cell walls of C. albicans to be stained by periodic acid-Schiff or labeled with fluorescent antibody. The component of the pathogen most resistant to physical or chemical treatment was the glucan, which lacked all immunological reactivity.