Invariant natural killer T (iNKT) cells rapidly produce copious amounts of multiple cytokines after activation, thereby impacting a wide variety of different immune reactions. However, strong activation of iNKT cells with α-galactosylceramide (αGalCer) reportedly induces a hyporeactive state that resembles anergy. In contrast, we determined here that iNKT cells from mice pretreated with αGalCer retain cytotoxic activity and maintain the ability to respond to TCR-dependent as well as TCR-independent cytokine-mediated stimulation. Additionally, αGalCer-pretreated iNKT cells acquired characteristics of regulatory cells, including production and secretion of the immunomodulatory cytokine IL-10. Through the production of IL-10, αGalCer-pretreated iNKT cells impaired antitumor responses and reduced disease in experimental autoimmune encephalomyelitis, a mouse model of autoimmune disease. Furthermore, a subset of iNKT cells with a similar inhibitory phenotype and function were present in mice not exposed to αGalCer and were enriched in mouse adipose tissue and detectable in human PBMCs. These data demonstrate that IL-10–producing iNKT cells with regulatory potential (NKT10 cells) represent a distinct iNKT cell subset.
Duygu Sag, Petra Krause, Catherine C. Hedrick, Mitchell Kronenberg, Gerhard Wingender
(A and B) Steady-state expression of Ki67 and BrdU (3-day pulse) in splenic iNKT cells from C57BL/6 control (B6, tinted area) or C57BL/6 mice injected 1 month earlier with 4 μg αGalCer (B6/αGC, black line). Representative data (A) and a summary graph (B) are shown. Numbers in the histograms denote the percentage of positive cells within the depicted gate from the indicated mice. (C–E) Expression of DNA (labeled with 7-AAD) and BrdU (3-day pulse) in splenic iNKT cells from C57BL/6 control (B6) or C57BL/6 mice injected 1 month earlier with 4 μg αGalCer (B6/αGC). Representative data (C) and a summary graph (D) are shown. Numbers in C denote the percentages in the respective rectangles. Definition of the cell-cycle stages is given in the left dot plot. M, mitosis. (E) Graphic representation of the frequency of 7-AAD– (S early) and 7-AAD+ (S late) cells, considering BrdU+iNKT cells. Representative data from at least 3 independent experiments (3–4 mice/group) are shown for each panel.