Molecular mechanism of blood monocyte adhesion to vascular endothelial cells.

The blood monocytes adhere to endothelial cells unstimulated and after stimulation by interleukin-1, tumor necrosis factor or other mediators. This process is mediated through specific molecules on both endothelial cells and monocytes. Using specific monoclonal antibodies and molecular cloning several families of molecules involved in leukocyte endothelial cell interaction have been defined. Leukocyte adhesion molecules include the three beta 2 integrins (CD11/CD18 molecules), VLA-4 and the L-Selectin. E-Selectin (ELAM-1), P-Selectin (GMP-140) and receptors of the immunoglobulin superfamily (ICAM-1, ICAM-2 and VCAM-1) are expressed on endothelial cells in basal conditions and after activation. It has been shown that these adhesive molecules are involved in blood monocyte adhesion to endothelial cells. Monocytes from patients with diabetes mellitus had an increased adhesion to endothelial cells in culture. As estimated by flow cytometry CD11b/CD18 expression on diabetic monocytes was increased. Pentoxifylline reduced CD11b/CD18 expression on normal and diabetic monocytes. This effect was associated to a decrease in monocyte adhesion to endothelial cells.