Adhesion

During inflammation leucocytes undergo various morphological changes associated with adherence, firstly they adopt a more spherical shape, then they roll, then they become stationary and flatten. During this process the membrane takes on a ruffelled appearance and there is a change in membrane receptors.

Binding of E-selectin with L-selectin results in very slow rolling and the onset of adherence. Tight adherence of leucocytes is thought to occur only after rolling. Following the interaction of E and L selectin, interaction of $\beta _2$ integrins (LFA-1, Mac-1) on leucocytes with ICAM-1 on the endothelium and the $\beta_1$ integrin (VLA-4) with VCAM-1 on the endothelium are thought to result in adherence of leucocytes onto the endothelium. It has been noted that binding of E to L selectin results in increased binding of $\beta _2$ integrins to ICAM-1.