CD1D
CD1D is the human gene that encodes the protein CD1d, a member of the CD1 (cluster of differentiation 1) family of glycoproteins expressed on the surface of various human antigen-presenting cells. They are non-classical MHC proteins, related to the class I MHC proteins, and are involved in the presentation of lipid antigens to T cells. CD1d is the only member of the group 2 CD1 molecules.
Biological significance
CD1d-presented lipid antigens activate a special class of T cells, known as Invariantnatural killer T (iNKT) cells, through the interaction with the T-cell receptor present on NKT membranes. When activated, NKT cells rapidly produce Th1 and Th2 cytokines, typically represented by interferon-gamma and interleukin 4 production.
Nomenclature
CD1d is also known as R3G1
Ligands
Some of the known ligands for CD1d are:
α-galactosylceramide (α-GalCer), a compound originally derived from the marine sponge Agelas mauritanius with no physiological role but great research utility.
α-glucuronyl- and α-galacturonyl- ceramides, a family of compounds of microbial origin which can be found, for example, on the cell wall of Sphingomonas, a ubiquitous Gram-negative bacterium. The related β-D-glucopyranosylceramide is accumulated in antigen-presenting cells after infection, where it serves to activate invariant NKTs (iNKTs), a special kind of NKT.