Lewis x antigen (Le^x)

Lewis x antigen is a cell-surface **trisaccharide carbohydrate antigen** defined by the structure Galβ1→4(Fucα1→3)GlcNAc[6]. It is classified as a type II histoblood group antigen and is expressed on glycolipids and glycoproteins of many cell types, particularly on granulocytes, some epithelial and endothelial cells, and as SSEA-1 in embryonic tissues[5][9]. The sialylated form (sialyl-Lewis x, CD15s) is an essential ligand for selectins (E-, P-, and L-selectin), mediating rolling and adhesion of leukocytes to endothelium during inflammation and facilitating tumor cell metastasis[1][7][8]. Lewis x antigen and its derivatives are overexpressed in various human cancers, making them targets for diagnostic and therapeutic antibodies. They also play significant roles in embryogenesis, immune cell recognition, and have been implicated in infectious disease processes as binding sites for particular pathogens and viruses[2][7].

Other names

Le^xCD15CD15s (for sialylated form, CD15s)Lewis X antigenSSEA-1 (Stage Specific Embryonic Antigen-1)3-Fucosyl-N-acetyllactosamine

**Selectin antagonism**: Drugs or antibodies disrupt Lewis x–selectin-mediated cell adhesion, inhibiting leukocyte recruitment or tumor metastasis[8].\n**Antibody-dependent cytotoxicity**: Monoclonal antibodies may induce immune cell–mediated killing of cancer cells expressing Lewis x[4].