TRAIL and inflammatory cytokine-mediated leukocyte adhesion. HUVECs were either left untreated or exposed to TRAIL, TNF-α, or IL-1β. (Ai) HL-60 cell adherence on HUVECs treated (for 18 hours) as indicated. Representative fields of the cultures are shown (original magnification × 10). (Aii) Cell adhesion was calculated as described in “Materials and methods” and is expressed as mean ± SD of 12 experiments, each performed in triplicate. ^*P < .05. (B) HUVECs were exposed to cytokines for 18 hours and expression levels of leukocyte adhesion molecules (ICAM-1, VCAM-1, and E-selectin) were evaluated by flow cytometry. The control (open) histograms represent the background fluorescence obtained from the staining of the same cultures with isotype-matched control Abs. One of 8 experiments with similar results is shown. (C) HUVECs were stimulated with TRAIL, TNF-α, or IL-1β for the indicated time intervals (0-45 minutes), and cell lysates were analyzed for degradation of IκBα and IκBβ by Western blotting. Equal loading of protein in each lane was confirmed by staining with the Ab to tubulin. One of 4 experiments with similar results is shown.