Abstract
Spleen cells from mice were shown to be capable of killing Cryptococcus neoformans cells in the absence of active complement. The number of viable C. neoformans cells did not vary significantly during the first 5hr of incubation period either in the presence or absence of spleen cells, but after 15hr incubation with spleen cells a considerable reduction in the number of viable yeast cells was observed. No significant difference related to age, sex or genetic background of mice in the killing activity of spleen cells was found. Cells with killing activity were plastic- and nylon wool-adherent. Treatment of spleen cells with carbonyl iron powder and magnet modestly reduced their activity. The activity of spleen cells was fairly diminished when they were treated with anti-mouse IgG antiserum plus complement. In contrast, anti-mouse IgM, anti-Thy 1, 2 and anti-asialo GM1 antisera, each in the presence of complement, had no effect. These results appear to indicate that the majority, if not all, of the effector cells belong to B lymphocyte lineage. The results obtained in the present study suggest that effector cells of the natural killing activity play a role in primary host defense against C. neoformans infection.
