Tracking the response of natural killer T cells to a glycolipid antigen using CD1d tetramers

A major group of natural killer (NK) T cells express an invariant V alpha 1 4(+) T cell receptor (TCR) specific for the lipoglycan alpha-galactosylcera mide (alpha-GalCer), which is presented by CD1d. These cells may have an im portant immune regulatory function, but an understanding of their biology h as been hampered by the lack of suitable reagents for tracking them in vivo . Here we show that tetramers of mouse CD1d loaded with alpha-GalCer are a sensitive and highly specific reagent for identifying V alpha 14(+) NK T ce lls. Using these tetramers, we find that alpha-GalCer-specific T lymphocyte s are more widely distributed than was previously appreciated, with populat ions of largely NK1.1(-) but tetramer-binding T cells present in the lymph nodes and the intestine. Injection of alpha-GalCer leads to the production of both interferon gamma and interleukin 4 by nearly all NK T cells in the liver and the: majority of the spleen within 2 h. These cells mostly disapp ear by 5 h, and they do not reappear after 1 wk. Curiously, tetramer-positi ve thymocytes do not rapidly synthesize cytokines, nor do they undergo decr eases in cell number after lipid antigen stimulation, although they express equivalent TCR levels. In summary, the data presented here demonstrate cha t alpha-GalCer-specific NK T cells undergo a unique and highly compartmenta lized response to antigenic stimulation.