Poly-N-acetyllactosamine (poly-LacNAc) (poly-LacNAc)

Poly-N-acetyllactosamine (poly-LacNAc) is a carbohydrate epitope consisting of repeating Gal-beta-1,4-GlcNAc units found on N-linked and O-linked glycans of cell surface glycoproteins. In the context of hematology, it is often referred to as the B-cell lactosamine antigen or the i/I antigen system, where linear chains (i-antigen) are converted to branched chains (I-antigen) during development. This glycan structure serves as a critical ligand for galectins, which regulate cell signaling, adhesion, and immune responses by forming a molecular lattice on the cell surface. In various B-cell malignancies and solid tumors, poly-LacNAc is frequently overexpressed or modified, contributing to tumor cell survival and immune evasion. Therapeutic strategies targeting this epitope include monoclonal antibodies designed to induce direct cell lysis and small molecule inhibitors aimed at disrupting galectin-glycan interactions. However, because these epitopes are also present on healthy erythrocytes and other tissues, managing off-target effects remains a significant challenge in clinical development.

Other names

B-cell lactosamine antigeni-antigenI-antigenLinear poly-N-acetyllactosamineBranched poly-N-acetyllactosamineGal-beta-1,4-GlcNAc-beta-1,3-repeats

Monoclonal antibodies or lectin-based inhibitors bind to the poly-LacNAc epitope on the surface of malignant B-cells or tumor cells to induce antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), or to block galectin-mediated immunosuppression and lattice formation.