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Phagocytosis of Candida albicans by concanavalin-A activated peritoneal macrophages
G Gaziri1, L C Gaziri, R Kikuchi
1Department of Pathology, Universidade Estadual de Londrina, Brazil.
Abstract:
We evaluated the effect of treatment of mice with concanavalin-A (Con-A) on the phagocytosis of glutaraldehyde-fixed Candida albicans by peritoneal macrophages. The mean number of unopsonized C. albicans blastoconidia phagocytosed 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 about four times (from 22.3+/-8.6 to 80.3+/-3.2) by Con-A. This increase in phagocytosis was about 50% inhibited by addition of mannan (50 microg) plus mannose (50 mM) to the assay medium, suggesting that it was mediated by mannose receptors (MR). Phagocytosis in vitro in the presence of fresh non-immune serum (5%) was also increased, from 84.3+/-5.0 for untreated macrophages 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 both the phagocytosis of C. albicans blastoconidia mediated by mannose receptors and by complement receptors.
Insights
Concanavalin-A (Con-A) treatment significantly enhances macrophage phagocytosis of Candida albicans. This Con-A induced increase in fungal clearance is mediated by both mannose and complement receptors.
Area of Science:
- Immunology
- Microbiology
Background:
- Peritoneal macrophages play a crucial role in host defense against fungal infections.
- Candida albicans is a common opportunistic fungal pathogen.
- Macrophage phagocytosis is a key mechanism for clearing Candida albicans.
Purpose of the Study:
- To investigate the effect of concanavalin-A (Con-A) on the phagocytic activity of mouse peritoneal macrophages against Candida albicans.
- To determine the mechanisms underlying Con-A-mediated enhancement of phagocytosis.
Main Methods:
- Mice were treated with Concanavalin-A (Con-A).
- Peritoneal macrophages were isolated and incubated with glutaraldehyde-fixed Candida albicans blastoconidia in vitro.
- Phagocytosis was assessed by quantifying the number of ingested blastoconidia per macrophage and the percentage of phagocytic cells.
- The role of mannose receptors (MR) and complement receptors was investigated by adding mannan and mannose or non-immune serum to the assay medium.
Main Results:
- Con-A treatment of donor mice doubled the mean number of unopsonized Candida albicans blastoconidia phagocytosed by peritoneal macrophages.
- The percentage of peritoneal cells phagocytosing blastoconidia increased approximately fourfold after Con-A treatment.
- Con-A-induced phagocytosis was partially inhibited by mannan and mannose, suggesting involvement of mannose receptors.
- Phagocytosis of opsonized blastoconidia was also enhanced by Con-A, with 100% of macrophages showing ingestion and a doubling of the mean number of ingested blastoconidia.
Conclusions:
- Concanavalin-A treatment significantly enhances the phagocytic capacity of mouse peritoneal macrophages against Candida albicans.
- The enhanced phagocytosis is mediated by both mannose receptors and complement receptors.
- Con-A represents a potential immunomodulatory agent for boosting macrophage-mediated clearance of fungal pathogens.