Modification of macrophage phagocytosis in murine cryptococcosis.

Normal C57BL/6J peritoneal cells exhibited a decreased phagocytosis when cultured with a cell wall antigen of Cryptococcus sp. and lymphocytes from mice infected with C. neoformans. Direct cell-to-cell interaction was not required in that supernatant fluids from cultures of lymphocytes from infected animals could be incubated with normal macrophage monolayers to give comparable suppression. The induction of the suppressor factor required specific cryptococcal antigen; however, suppression at the macrophage level was nonspecific in that the phagocytosis of C. neoformans and Saccharomyces cerevisiae were both decreased. Suppression appeared with lymphocyte supernatants taken from mice infected for 14 days and thereafter. The factor was heat stable, trypsin sensitive, and allospecific.