Cytokines such
as TNF and Il-1 induce the production of selectins, chemokines, and adhesion
molecules on the inner surface of the endothelial cells that form the blood
vessels. Eventually integrins on the surface of the leukocyte bind to adhesion
molecules on the inner surface of the vascular endothelial cells. The leukocytes
flatten out and squeeze between the endothelial cells, leaving the blood
vessels and entering the tissue.
