Evidence for the participation of proteinases released by Candida albicans in the early killing of peritoneal macrophages in vitro

RESUMO

We have investigated the possibility that proteinases released by Candida albicans participate in the early killing of three types of mice peritoneal macrophage (resident, thioglycollate-elicited, or Con-A-activated)in vitro. Phagocytic assays were performed by incubation of macrophages and C. albicans together at a 110 ratio for 30 min at 37 grade C in RPMI medium buffered to pH 7.0 with 12 mM Hepes without serum. With no albumin added to the medium, the medium, the macrophages were 85% to 100% damaged and unviable, to a greater extent than expected from the proportion of phagocytic cells containing germ tubes. When 10 mg/ml of albumin was added to the medium, however, 90% of the macrophages remained viable for the 2 hours of the phagocytic assay, suggesting that albumin may have acted as a substrate for or inhibitor of proteinases released by C. albicans, thereby protecting the macrophage from the proteolytic action of the proteinases. The phagocytosis of IgG-coacted erythrocytes was reduced to 43% when IgG was preincubated with the supernatant from C. albicans cultures, but the addition of 10 mg/ml albuumin or of 5 ug/ml pepstatin (an inhibitor of C. albicans acid proteinases) to the same supernatans prevented the effect on phagocytosis of IgG-coated erythrocytes. These results suggest that proteinases released from C. albicans are involved in the early killing of macrophages