Table 1.

Salient Features of the CD1 Antigen Presentation System

CD1 isoform	Groove volume	TCR	TCR variability: T cell subset designation	Antigens recognized	References
CD1a	1.35 nm3	αβ	diverse	sulfatide, PE, PI, PC, lyso-PC, fatty acids, squalene, wax esters, dideoxymycobactin	[27, 28, 30, 107]
CD1b	2.20 nm3	αβ	diverse	sulfatide, mycolic acid, glycerol monomycolate, diacylated sulphoglycolipids	[107–110]
		αβ	semi-invariant: GEM T	glucose monomycolate	[35]
		αβ	biased: LDN5-like T	glucose monomycolate	[36]
CD1c	1.78 nm3	αβ	diverse	phosphomycoketide, mannosyl-phosphomycoketide, lipopeptides	[41, 111]
		γδ	diverse	sulfatide, lyso-PC, phosphomycoketide, mannosyl-phosphomycoketide	[43, 107]
CD1d	1.65 nm3	Type I NKT or iNKT cells:
		αβ	semi-invariant: Vα14 (mouse) or Vα24 (human) NKT	α-GalCer, β-GalCer, α-GlcCer, α-GalACer, α-GalDAG, α-GlcDAG, cholesteryl α-glucoside, asperamide B, GD3, iGb3, PE, PI, PC, lyso-PC, lysopeptidophosphoglycan	[50–59, 74, 77, 78, 112–116]
		αβ	semi-invariant: Vα10 NKT	α-GalCer, α-GlcCer, α-GlcADAG	[81]
		Type II NKT, dNKT or vNKT cells:
		αβ	biased: sulfatide-reactive dNKT	sulfatide, β-GlcCer, β-GalCer	[62, 107, 117]
		αβ	diverse: “atypical” dNKT	α-GalCer	[97]
		αβ	diverse: non-sulfatide-reactive dNKT	PG, PI, cardiolipin, lyso-PE non-lipid small molecules (e.g., PPBF), peptides (synthetic, ovalbumin-derived, collagen-derived)	[60, 61, 63, 98, 99, 102]
		TCRγδ+ NKT cells:
		γδ	biased	cardiolipin	[118]
CD1e	2.00 nm3	-	-	sulfatide, PI, dimannosylated PI, diacylated sulphoglycolipids, hemi-bis(monoacylglycero)-phosphate	[105, 106]

Abbreviations: dNKT, diverse NKT; GalCer, galactosylceramide; GalACer, galacturonosylceramide; GalADAG, galacturonosyldiacylglycerol; GalDAG, galactosyldiacylglycerol; GD3, ganglioside D3; GEM, germline-encoded mycolyl-specific; GlcCer, glucosylceramide; iGb3, isoglobotrihexosylceramide; iNKT, invariant NKT; NKT, natural killer T; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; PI, phosphatidylinositol; vNKT, variant NKT; PPBF, phenyl 2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonate.