Immune recognition of Candida albicans β-glucan by dectin-1

β(1,3)-glucans represent 40% of the cell wall of the yeast Candida albicans. The dectin-1 lectin-like receptor has shown to recognize fungal β(1,3)-glucans and induce innate immune responses. The importance of β-glucan-dectin-1 pathways for the recognition of C. albicans byhumanprimary blood cells has not been firmly established. In this study we demonstrate that cytokine production by both human peripheral blood mononuclear cells and murine macrophages is dependent on the recognition of β-glucans by dectin-1. Heat killing of C. albicans resulted in exposure of β-glucans on the surface of the cell wall and subsequent recognition by dectin-1, whereas live yeasts stimulated monocytes mainly via recognition of cell-surface mannans. Dectin-1 induced cytokine production through the following 2 pathways: Syk-dependent production of the T-helper (Th) 2-type anti-inflammatory cytokine interleukin-10 and Toll-like receptor-Myd88-dependent stimulation of monocyte-derived proinflammatory cytokines, such as tumor necrosis factor-α. In contrast, stimulation of Th1-type cytokines, such as interferon-γ, by C. albicans was independent of the recognition of β-glucans by dectin-1. In conclusion, C. albicans induces production of monocyte-derived and T cell- derived cytokines through distinct pathways dependent on or independent of dectin-1. © 2007 by the Infectious Diseases Society of America. All rights reserved.