Increased plasma GlyCAM-1, a mouse L-selectin ligand, in response to an inflammatory stimulus.

GlyCAM-1 (glycosylation-dependent cell adhesion molecule-i) is one ofthe sialomucin-like ligands for L-selectin, which is a member ofthe selectin family and mediates initial adhesion of leukocytes to specialized high endothelial venules in lymph nodes and venules at sites of inflammation. G1yCAM-1, lacking a transmembrane domain, is supposed to be secreted into the blood. To understand the functional role of secreted G1yCAM-!, we performed sandwich enzymelinked immunosorbent assay to measure G1yCAM-! plasma levels after inflammatory stimulus. BALB/c mice were injected with complete Freund’s adjuvant (CFA) in the hind footpads; serum levels of G1yCAM-! and L-selectin bound to G1yCAM-! and several inflammatory cytokines, including interleukin-6 (IL-6), were measured at various intervals. IL-6 showed a significant increase 3 h after CFA stimulation. G1yCAM-1 was increased at 3 h, reached peak levels at 12 h, and gradually decreased thereafter. Levels of L-selectin bound to the plasma G1yCAM-1 changed over a similar time course, reached peak at 12 h after, and then began to decrease. The binding of L-selectin to plasma G1yCAM-! was completely eliminated with the presence of ethyleneglycol-bis( 3-aminoethylether)-N,N’tetraacetic acid, showing the calcium dependency of this binding. These findings show that G1yCAM-1 release is enhanced by inflammatory sthnulation and also suggest that released plasma G1yCAM-1 may trap, at least in part, soluble L-selectin shed from stimulated leukocytes to neutralize each other. J. Leukoc. Biol. 60: 593-597; 1996.