Tissue-Specific Distribution of iNKT Cells Impacts Their Cytokine Response

Three subsets of invariant natural killer T (iNKT) cells have been identified, NKT1, NKT2, and NKT17, which produce distinct cytokines when stimulated, but little is known about their localization. Here, we have defined the anatomic localization and systemic distribution of these subsets and measured their cytokine production. Thymic NKT2 cells that produced interleukin-4 (IL-4) at steady state were located in the medulla and conditioned medullary thymocytes. NKT2 cells were abundant in the mesenteric lymph node (LN) of BALB/c mice and produced IL-4 in the T cell zone that conditioned other lymphocytes. Intravenous injection of alpha-galactosylceramide activated NKT1 cells with vascular access, but not LN or thymic NKT cells, resulting in systemic interferon-gamma and IL-4 production, while oral alpha-galactosylceramide activated NKT2 cells in the mesenteric LN, resulting in local IL-4 release. These findings indicate that the localization of iNKT cells governs their cytokine response both at steady state and upon activation.