Cell surface lectins in the immune system

Emerging evidence establishes that the immune system employs carbohydrates as recognition determinants for various cellular interactions. The best understood case is provided by the selectin family (L-, E- and P-selectin), which are found on leukocytes or endothelial cells and mediate a variety of leukocyte-endothelial interactions. By virtue of C-type lectin domains, these receptors mediate adhesion by recognizing specific carbohydrate-based ligands on partner cells. This review will summarize current research on the selectins and their ligands. Additionally, several leukocyte receptors, for which lectin activity has been demonstrated or inferred to exist, will be considered briefly.