sialyl-Lewis X


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sialyl-Lewis X

A tetrasaccharide carbohydrate antigen that attaches to O-glycans on cell surfaces.

Physiology
The sialyl-Lewis X determinant, E-selectin ligand carbohydrate, is constitutively expressed on granulocytes and monocytes, and mediates their extravasation during inflammation; resting Th2 and B cells do not express sialyl-Lewis X, but do so once activated. Sialyl-Lewis X also plays a key role in cell recognition during fertilisation, facilitating adherence of sperm to the egg. 

Pathology
Defective sialyl Lewis X synthesis results in leukocyte adhesion deficiency type 2, an immunodeficiency. Decreased sialyl Lewis X synthesis can be due to a defect in fucosyltransferase, which impairs the glycosylation of glycosphingolipid.