Dendritic Cells, Part 1

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Science  29 Apr 2005:
Vol. 308, Issue 5722, pp. 603
DOI: 10.1126/science.308.5722.603b

The recognition of the molecular patterns of pathogens by innate immune receptors is a well-established function of the Toll-like receptor (TLR) family; similar activities are now being ascribed to other families of host cell proteins. For example, the C-type lectin Dectin-1 enables phagocytosis of yeast by scavenger cells by binding the yeast cell wall carbohydrates (β glucans), and it has been shown to act as a coreceptor for TLR2, leading to inflammatory cytokine expression.

Rogers et al. show that Dectin-1 can signal directly to initiate cytokine transcription. The production of interleukin-2 (IL-2) and IL-10 could be induced upon exposure of dendritic cells to a yeast cell wall extract and was partially blocked by a soluble β glucan. An equivalent phenotype could be conferred on a B cell hybridoma line (LK cells) by transduction of Dectin-1. Transcription of both cytokines was dependent on the intracellular tyrosine kinase, Syk, which was recruited by the immunoreceptor tyrosine-based activation motif in the cytoplasmic tail of Dectin-1. The distinct cytokine profiles induced by Dectin-1 in the context of Syk signals, versus co-signaling with TLR2, suggest flexibility in innate pattern recognition that could be tailored for a pathogen- specific adaptive immune response. — SJS

Immunity 22, 509 (2005).

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