Table 1.

Mammalian glycan structures that are linked to immune functions

	Glycan*	Enzymes‡	Function	Recognition§
sLex		ST3Gal4, ST3Gal6, β1,4GalT1, Fut4 and Fut7	Trafficking, adhesion and signalling	E- and P-selectin
6-sulpho-sLex		ST3Gal4, GlcNAc6ST1, GlcNAc6ST2, Fut4 and Fut7	Lymphocyte homing	L-selectin
Core 1 O-glycan		ST3Gal1	CD8+ T-cell apoptosis	Unknown
Terminal GlcNAc		GnTs	IgA nephropathy and complement activation	Integrins
N-acetyl-lactosamine and polylactosamine		β1,4GalTs and β1,3GnTs	T-cell-mediated tumour rejection, fetal–maternal tolerance and DC function	Galectins
β1,6 N-glycan branch		GnT5	TCR activation threshold	Galectin-3
Sia6LacNAc		ST6Gal1	BCR activation threshold	CD22
Hybrid N-glycan		αM-II	Deficiency causes SLE-like syndrome in mice	Mannose-binding lectin (or lectins)
O-fucose glycan		β1,3GlcNAcTs and Pofut1	Lymphocyte development and activation, myeloid and DC development, and NK-cell toxicity	Notch
O-glucose glycan		O-glucosyltransferase (Rumi)	Notch signalling	Notch
Hyaluronan		Hyaluronan synthases	Innate immunity, response to infection	TLR2 and TLR4
N-glycan		Fut8	TGFβ1 receptor ligand binding and signalling	TGFβ1

^*Glycan structure is indicated using the symbol nomenclature for monosaccharides; see FIG. 1 for further information.

^‡Glycosyltransferase and glycosidase enzymes that are known to be responsible for the presence of the indicated glycan linkages, whether owing to their regulated expression or lack of expression.

^§Recognition proteins that include classically defined lectins, which function by binding to the highlighted glycan structures. αM-II, α-mannosidase-II; β1,4GalT, β1,4-galactosyltransferase; β1,3GnT, β1,3-glucosaminyltransferase; BCR, B-cell receptor; DC, dendritic cell; Fut, fucosyltransferase; GCNT1, core 2 β1,4-glucosaminyltransferase 1; GlcNAc, β-N-acetylglucosamine; GlcNAc6ST, glycan sulphotransferase; GnT, N-acetylglucosaminyltransferase; NK, natural killer; Pofut1, protein O-fucosyltransferase; SLE, systemic lupus erythematosus; sLe^x, sialyl-Lewis-X; ST3Gal, α2,3-sialyltransferase, TCR, T-cell receptor; TGFβ1, transforming growth factor β1; TLR, Toll-like receptor.