CYCLOSPORINE ENHANCES LEUKOCYTE ADHESION TO VASCULAR ENDOTHELIUM UNDER PHYSIOLOGICAL FLOW CONDITIONS

We investigated the effect of cyclosporine (CyA) on leukocyte adhesion to endothelium under flow conditions, Confluent human umbilical vein endothelial cells (HUVECs) were incubated for 24 hours with CyA (1, 5, and 10 mu mol/L) and then exposed to a total human leukocyte suspensi on in a parallel plate flow chamber under laminar flow (1.5 dynes/cm(2 )). Human umbilical vein endothelial cells stimulated with interleukin -1 beta (20 U/mL) were used as a positive control. Adherent cells were measured by digital image analysis, Results showed that CyA dose-depe ndently increased the number of leukocytes adhering to HUVECs compared with control cells, Leukocyte adhesion markedly increased on HUVECs i ncubated with interleukin-1 beta, one of the most potent inducers of e ndothelial cell adhesiveness, Exposure of endothelial cells to CyA did not affect the number of rolling leukocytes, which was similar to con trol values, To examine the role of adhesion molecules in CyA-induced leukocyte adhesion, HUVECs were incubated with monoclonal antibodies a gainst intercellular adhesion molecule-1 (ICAM-1), vascular adhesion m olecule-1 (VCAM-1), and E-selectin before adhesion assay. Functional b locking of ICAM-1, VCAM-1, and E-selectin on endothelial cells signifi cantly inhibited CyA (10 mu mol/L)-induced leukocyte adhesion. Confoca l fluorescence microscopy studies showed that CyA induced an increase in the endothelial surface expression of ICAM-1, VCAM-1, and E-selecti n. Pretreatment of leukocytes with the platelet activating factor rece ptor antagonist L659,989 significantly reduced the number of leukocyte s adhering to CyA-treated HUVECs. We suggest that CyA enhances leukocy te adhesion to endothelium by upregulating adhesive proteins on endoth elial surface membrane, Blocking leukocyte receptor for platelet-activ ating factor partially prevents adhesion, suggesting a role for endoth elial cell-associated platelet-activating factor in the interaction be tween leukocytes and CyA-treated endothelium. (C) 1996 by the National Kidney Foundation, Inc.