The selectins are subtype IV C-type lectins defined the presence of the C-type lectin CRD, an epidermal growth factor-like domain and a variable number of complement regulatory protein-like repeat domains.
Galectin-1 is expressed by antigen-stimulated T cells, activated B cells and by macrophages.
The action of galectin-1 in these systems is to stimulate apoptosis resulting in cell death.
P-selectin is constitutively stored in secretory granules of platelets and endothelial cells. IL-1 and TNF-α) these cells present P-selectin to the cell surface.
Through this mechanism, P-selectin is involved in mediating very early responses of leukocytes to inflammatory signals.
E-selectin is also synthesized by endothelial cells but is not constitutively present.