Cultured human umbilical vein endothelial cell (EC) monolayers stimulated with 10 ng/ml tumor necrosis factor demonstrate a time-dependent increase in the expression of the vascular cell adhesion molecule-1 (VCAM-1) with maintained maximal expression at 24 h following EC activation. A monoclonal antibody (mAb) directed against VCAM-1 (1G11) significantly inhibited the adhesion of eosinophils, but not neutrophils, to EC, which had been activated by tumor necrosis factor-alpha for 24 h, but only when eosinophils had been pretreated with an mAb directed against the common beta chain of the CD11/CD18 complex. In the absence of pretreatment with anti-CD18, mAb 1G11 had no significant effect on eosinophil adhesion. These results suggest that eosinophils bind to VCAM-1. However, the functional capacity in this model of the eosinophil receptor for VCAM-1 is likely to be minor compared with the activity of the CD11/CD18 leukocyte adhesion molecules.