Figure 1.

The migration of leukocytes towards an inflammatory focus is a sequential process that includes the tethering of leukocytes with endothelial cells (1^st step), the rolling of leukocytes on endothelium (2^nd step), the transient firm adhesion of leukocytes (3^rd step), and their polarization and extravasation (4^th step), reaching thus the inflamed tissue (upper panel). When LFA-1 or Mac-1 integrins are blocked with antibodies of synthetic peptides, the firm adhesion of leukocytes is inhibited and these cells return to the bloodstream (middle panel), but when these integrins are induced to activate, increasing their avidity for their endothelial ligands (ICAM-1, -2), leukocytes remain firmly adhered to endothelium, with no progression to the 4^th step or extravasation (lower panel). As stated in the text, leukadherins exert the latter effect, and are able to inhibit the inflammatory phenomenon.