Friday, June 26, 2015

Activated NKT Cells Can Condition Different Splenic Dendritic Cell Subsets To Respond More Effectively to TLR Engagement and Enhance Cross-Priming.

Osmond TL, Farrand KJ, Painter GF, Ruedl C, Petersen TR, Hermans IF.
Activated NKT Cells Can Condition Different Splenic Dendritic Cell Subsets To Respond More Effectively to TLR Engagement and Enhance Cross-Priming. J Immunol. 2015 Jun 15. pii: 1401751. [Epub ahead of print]

The function of dendritic cells (DCs) can be modulated through multiple signals, including recognition of pathogen-associated molecular patterns, as well as signals provided by rapidly activated leukocytes in the local environment, such as innate-like T cells. In this article, we addressed the possibility that the roles of different murine DC subsets in cross-priming CD8+ T cells can change with the nature and timing of activatory stimuli. We show that CD8α+ DCs play a critical role in cross-priming CD8+ T cell responses to circulating proteins that enter the spleen in close temporal association with ligands for TLRs and/or compounds that activate NKT cells. However, if NKT cells are activated first, then CD8α- DCs become conditioned to respond more vigorously to TLR ligation, and if triggered directly, these cells can also contribute to priming of CD8+ T cell responses. In fact, the initial activation of NKT cells can condition multiple DC subsets to respond more effectively to TLR ligation, with plasmacytoid DCs making more IFN-α and both CD8α+ and CD8α- DCs manufacturing more IL-12. These results suggest that different DC subsets can contribute to T cell priming if provided appropriately phased activatory stimuli, an observation that could be factored into the design of more effective vaccines.

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