Phagocytosis of Candida albicans by concanavalin-A activated peritoneal macrophages

We evaluated the effect of treatment of mice with concanavalin-A (Con-A) on the phagocytosis of glutaraldehyde-fixed Candida albicans by peritoneal ma crophages. The mean number of unopsonized C. albicans blastoconidia phagocy tosed in vitro by peritoneal macrophages was doubled (from 1.3 +/- 0.1 to 2 .7 +/- 0.14) by pre-treatment of the donor mice with Con-A. The percent of peritoneal cells phagocytosing the blastoconidia in vitro was increased abo ut four times (from 22.3 +/- 8.6 to 80.3 +/- 3.2) by Con-A. This increase i n phagocytosis was about 50% inhibited by addition of mannan (50 mu g) plus mannose (50 mM) to the assay medium, suggesting that it was mediated by ma nnose receptors (MR). Phagocytosis in vitro in the presence of fresh non-im mune serum (5%) was also increased, from 84.3 +/- 5.0 for untreated macroph ages to 100% for Con-A activated peritoneal macrophages and the mean number of opsonized C. albicans blastoconidia increased from 2.3 +/- 0.1 to 4.6 /- 0.1. These results suggest that treatment of mice with Con-A increased b oth the phagocytosis of C. albicans blastoconidia mediated by mannose recep tors and by complement receptors.