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) Splenocytes from C57BL/6 control or C57BL/6 mice i.v. injected 1 month earlier with 4 μg αGalCer (αGalCer-pre) were stained for FOXP3 expression. Cells depicted are gated spleen iNKT cells (live TCRβ+CD19–CD8α–CD1d-αGalCer tetramer+) or spleen CD4+CD25+ T cells (live TCRβ+CD19–CD8α–) from mice treated in the indicated manner. (B) Expression of BCL6 in (left panel) or CD127 on (right panel) splenic iNKT cells from C57BL/6 control (αGalCer-pre: No) or C57BL/6 mice i.v. injected 6 days or 33 days earlier with 4 μg αGalCer (αGalCer-pre: Yes). Representative data are shown in Supplemental Figure 9. (C–E) C57BL/6 control (B6) or C57BL/6 mice injected 4–6 weeks earlier with 4 μg αGalCer (B6/αGC) were rechallenged with 1 μg αGalCer injected i.v., and 90 minutes later splenocytes were purified and incubated for 2 hours in vitro in the presence of protein transport inhibitors. Expression levels of IL-10 and IL-17A (C) or CD4 and CD49d (D and E) were then determined on iNKT cells. Representative data (D) and a summary graph (E) are shown. Numbers in the histograms in D denote the percentage of positive cells within the depicted gate. Representative data from at least 3 independent experiments are shown.