Tissue-Specific Distribution of iNKT Cells Impacts Their Cytokine Response

• IL-4 secreting NKT2 cells are localized in the thymic medulla
• Splenic NKT1 cells are in red pulp and NKT2 cells in T cell zone
• Intravenous injection of αGalCer activates NKT1 cells in spleen and liver
• Oral administration of αGalCer stimulates NKT2 cells in mesenteric LN

SummaryThree 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 α-galactosylceramide activated NKT1 cells with vascular access, but not LN or thymic NKT cells, resulting in systemic interferon-γ and IL-4 production, while oral α-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.