SELL (selectin L) encodes a calcium-dependent lectin that mediates cell adhesion through binding to glycoproteins on neighboring cells 123. The protein functions primarily in leukocyte recruitment by promoting initial tethering and rolling of leukocytes on endothelial cells, particularly in high endothelial venules of peripheral lymph nodes 12. SELL expression is associated with immune cell phenotypes and inflammatory responses. In cardiovascular disease, SELL polymorphisms (rs2205849 and rs2229569) show age-dependent associations with acute coronary syndrome risk, potentially increasing risk in patients over 55 years 4. In glioblastoma, SELL exhibits causal association with elevated tumor risk, functioning through cerebrospinal fluid metabolite pathways that mediate approximately 16% of its effect on disease development 5. In triple-negative breast cancer, SELL-expressing tumor-infiltrating NK cells display immunosuppressive phenotypes characterized by IL-10 secretion, with elevated SELL+ NK cell proportions associated with poor progression-free survival following checkpoint blockade immunotherapy 6. These findings establish SELL as a multifunctional adhesion molecule with distinct roles in normal immune homeostasis and pathological immune suppression in cancer contexts.