Natural killer (NK) T cells are a subset of mature T lymphocytes that express an α/β TCR together with markers characteristic of NK cells such as NK1.1 1,2. In contrast to conventional T cells, which recognize small peptides bound to polymorphic MHC class I or class II molecules, TCRs on NK T cells recognize glycolipids associated with the monomorphic MHC-like CD1d molecule. As expected from their restricted specificity, most NK T cells utilize a limited TCR repertoire comprising an invariant Vα14–Jα281 chain paired preferentially to Vβ8.2 (in the mouse) or the homologous invariant Vα24–JαQ chain paired to Vβ11 in humans.
At present, the physiological CD1d-associated ligands recognized by the semiinvariant TCR on NK T cells are not known. However a synthetic glycolipid, α-galactosylceramide (α-GalCer) has been shown to selectively activate NK T cells expressing the Vα14/Vβ8.2...
