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Effect of activation on adhesion of flowing neutrophils to cultured endothelium: time course and inhibition by a calcium channel blocker (nitrendipine)

1 Adhesion of neutrophils to vascular endothelium plays an important role in inflammation and thrombosis. Modulation of adhesion may be therapeutic in these conditions. 2 A flow model was used to quantify adhesion of neutrophils to human cultured umbilical vein endothelial cells. The time course of the neutrophil response to activation by N‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP, 10−7 m) was studied and the inhibitory effects of the calcium‐channel blockers, nitrendipine and nifedipine, were investigated. 3 Neutrophils adhered firmly to the endothelial cells without rolling, but initial attachment was highly dependent on shear stress; doubling the stress from 0.05 to 0.1Pa decreased the number of neutrophils adhering by over 80%. 4 Adhesion rapidly increased after activation of neutrophils by fMLP, peaking at 1–3 min post‐treatment, and then decreased over the next 10–12 min. A monoclonal antibody to the β2‐integrin component CD18 inhibited adhesion by over 80% for activated or unactivated cells. 5 The Ca‐channel blocker, nitrendipine, but not nifedipine, significantly inhibited the fMLP‐induced increase of adhesion in a dose‐dependent manner (10−8 to 10−6 m). Dihydropyridines may be useful agents for modifying neutrophil function.