| 15746081 |
Ota T, Takeda K, Akiba H, Hayakawa Y, Ogasawara K, Ikarashi Y, Miyake S, Wakasugi H, Yamamura T, Kronenberg M, Raulet DH, Kinoshita K, Yagita H, Smyth MJ, Okumura K: IFN-gamma-mediated negative feedback regulation of NKT-cell function by CD94/NKG2. Blood. 2005 Jul 1;106(1):184-92. Epub 2005 Mar 3.
Activation of invariant natural killer T (iNKT) cells with CD1d-restricted T-cell receptor (TCR) ligands is a powerful means to modulate various immune responses. However, the iNKT-cell response is of limited duration and iNKT cells appear refractory to secondary stimulation. Here we show that the CD94/NKG2A inhibitory receptor plays a critical role in down-regulating iNKT-cell responses. Both TCR and NK-cell receptors expressed by iNKT cells were rapidly down-modulated by priming with alpha-galactosylceramide (alpha-GalCer) or its analog OCH [(2S,3S,4R)-1-O-(alpha-D-galactopyranosyl)-N-tetracosanoyl-2-amino-1,3,4-n onanetriol)]. TCR and CD28 were re-expressed more rapidly than the inhibitory NK-cell receptors CD94/NKG2A and Ly49, temporally rendering the primed iNKT cells hyperreactive to ligand restimulation. Of interest, alpha-GalCer was inferior to OCH in priming iNKT cells for subsequent restimulation because alpha-GalCer-induced interferon gamma (IFN-gamma) up-regulated Qa-1b expression and Qa-1b in turn inhibited iNKT-cell activity via its interaction with the inhibitory CD94/NKG2A receptor. Blockade of the CD94/NKG2-Qa-1b interaction markedly augmented recall and primary responses of iNKT cells. This is the first report to show the critical role for NK-cell receptors in controlling iNKT-cell responses and provides a novel strategy to augment the therapeutic effect of iNKT cells by priming with OCH or blocking of the CD94/NKG2A inhibitory pathway in clinical applications. |
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