Stimulation of a subset of natural killer T cells by CD103+ DC is required for GM-CSF and protection from pneumococcal infection

Abstract

Innate-like Tcells, including invariant natural killer Tcells, mucosal-associated invariant Tcells, and γδ Tcells, are present in various barrier tissues, including the lung, where they carry out protective responses during infections. Here, we investigate their roles during pulmonary pneumococcal infection. Following infection, innate-like Tcells rapidly increase in lung tissue, in part through recruitment, but Tcell antigen receptor activation and cytokine production occur mostly in interleukin-17-producing NKT17 and γδ Tcells. NKT17 cells are preferentially located within lung tissue prior to infection, as are CD103+ dendritic cells, which are important both for antigen presentation to NKT17 cells and γδ Tcell activation. Whereas interleukin-17-producing γδ Tcells are numerous, granulocyte-macrophage colony-stimulating factor is exclusive to NKT17 cells and is required for optimal protection. These studies demonstrate how particular cellular interactions and responses of functional subsets of innate-like Tcells contribute to protection from pathogenic lung infection.