NK-T cells are a small and unusual class of T cells that recognize lipid, rather than protein-derived antigen. The structures responsible for presenting lipid antigens--the CD1 molecules--have been studied for some time, yet the intracellular requirements for this mode of antigen presentation have not been defined. Prigozy et al. report that as for protein antigen, intracellular processing may be an obligate part of presentation of lipids to T cells. Using a precursor of a model glycosphingolipid antigen, the authors observed that only when the enzymatic machinery of the lysosmal compartment was intact could antigen recognition by NK-T cells take place. This process involved the removal of a terminal sugar group by the enzyme α-galactosidase, thus permitting the association of the modified lipid with the presenting molecule CD1d.
T. I. Prigozy, O. Naidenko, P. Qasba, D. Elewaut, L. Brossay, A. Khurana, T. Natori, Y. Koezuka, A. Kulkarni, M. Kronenberg, Glycolipid antigen processing for presentation by CD1d molecules. Science 291, 664-667 (2001). [Abstract] [Full Text]