Compared to other diseased cells, malignant tumor cells often exhibit modified surface glycosylation patterns, potentially altering recognition by host immune cells.
Natural killer (NK) cells are sentinels of cancer immunosurveillanc system and express multiple receptors that allow for discrimination between healthy and malignant cells.
In this issue of the Journal of Clinical Investigation, Stephan von Gunten and colleagues at the University of Bern determined that ligands of the inhibitory sialic acid-binding lectins Siglec-7 and Siglec-9 are expressed on the surface of multiple tumor cell types, and that expression of these ligands protects tumor cells from NK cell responses.
Evaluation of NK cells in healthy donors revealed the presence of a Siglec-9-expressing cytotoxic NK cell population with enhanced chemotactic potential.
Interestingly, the Siglec-9-expressing NK cell population was reduced in peripheral blood from patients with colon adenocarcinoma and malignant melanoma. These data suggest that targeting Siglec-7 and Siglec-9 ligands may enhance NK cell-based cancer therapies.