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.
Authors
Duygu Sag, Petra Krause, Catherine C. Hedrick, Mitchell Kronenberg, Gerhard Wingender
(A) Upper panel: Normalized data on αGalCer-specific in vivo cytotoxicity in spleen 4 hours after injection of primary splenic B cell targets into C57BL/6 (B6) and previously thymectomized C57BL/6 mice (B6/ThX) (3 mice/group), which were either left untreated (control) or i.v. injected 1 month earlier with 4 μg αGalCer. iNKT cell–deficient Jα18–/– mice injected with B cell targets provided the negative control. P = 0.797 for B6 versus B6/ThX. Lower panel: Relative frequencies of splenic iNKT cells in the indicated groups. P = 0.372 for B6 versus B6/ThX. (B and C) Splenocytes enriched for iNKT cells from the indicated mice were incubated for 5 hours in plates coated with αCD3ε antibodies in the presence of αCD107a and αCD107b antibodies. Representative data (B) and a summary graph (C) are shown. Numbers in B denote the geometric mean values. (D) Lung metastases in B6 control or B6/αGalCer mice that were i.v. injected with 1 × 105 B16-CD1d melanoma cells (4–7 mice/group). B16-CD1d cells were either untreated or loaded in vitro with αGalCer (250 ng/ml, 1 hour), as indicated. Indicated mice were additionally i.v. injected 3 times (days 0, 4, and 7) with 1 μg αGalCer. Representative data from at least 2 independent experiments are shown in each panel.