CD1D is the humangene that encodes the proteinCD1d,[5] 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.
α-galactosylceramide (α-GalCer), a compound originally derived from the marine sponge Agelas mauritanius[6] with no physiological role but great research utility.
iGb3, a self antigen which has been implied in iNKT selection.[8]
HS44, a synthetic amino cyclitolic ceramide analogue which has less contact with the TCR, activating iNKTs in a more constrained way than α-GalCer (specially in relation to Th2 cytokines production) and thus being more interesting for therapeutic use.[9]
CD1d tetramers are protein constructs composed of four CD1d molecules joined together and usually fluorescently labelled, used to identify NKT cells or other CD1d-reactive cells. In particular, type I NKT cells and some type II NKT cells are stained by them. A differentiation of these two types can be obtained in human by using an antibody against the TCR Vα24 chain, which is specific of type I NKT cells.[10]
Although they are the most widely used of CD1d oligomers, sometimes CD1d dimers (two units) or pentamers (five units) are used instead.[10]
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