Platelet-activating factor , binding synthesis

After infection and immune cell activation, endothelial cells are variously activated to bind peripheral blood leucocytes. Bacterial toxins such as lipopolysaccharide (LPS), inflammatory cytokines such as tumour necrosis factors a and (5 (TNFa and TNFP) and interleukin-1 (5 (IL-ip) increase the synthesis of cell surface E- and P-selectins in endothelial cells. Histamine and thrombin increase PM P-selectins in endothelial cells and platelets. L-selectins are constitutively expressed in monocytes and lymphocytes. The selectins are involved in the initial adhesion of leucocytes with endothelial cells via selectin-selectin receptor interactions, for example, monocyte L-selectin-endothelial L-selectin ligand binding and T-lymphocyte-endothelial selectin-integrin interactions. This initial phase of leucocyte-endothelial adhesion enables an early stage of leucocyte rolling through successive formation and breakage of adhesive interactions. 

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