Inhibition of IL-1β-induced upregulation of E-selectin in glEND.2 cells by ALP. (a) Inhibition of IL-1β-induced upregulation of E-selectin in glEND.2 cells by antileukoproteinase (ALP). Determination of E-selectin expression on glEND.2 cells was performed by FACS analysis after staining with a biotinylated anti-E-selectin mAb and phycoerythrin-labelled-streptavidin. The histograms obtained after gating on glEND.2 cells for forward and sideways light-scattering properties and counting of 5,000 events demonstrate the increasing surface expression of E-selectin in response to stimulation with IL-1β (curve shifted furthest to the right) compared with the unstimulated control (leftmost curve). The intermediate curve represents the E-selectin distribution on glEND.2 cells pretreated with ALP (2 μM) before stimulation with IL-1β. (b) Inhibition of E-selectin expression by ALP. Mean fluorescence intensities were determined as a measure of the E-selectin expression levels in six independent experiments and used to calculate the mean and SEM for the following experimental conditions of glEND.2 cell activation: no stimulus (- IL-1β control), IL-1β stimulus (+IL-1β), IL-1β stimulation after pretreatment with ALP for 2 hours (+IL-1β ALP 2 μM and +IL-1β ALP 12 μM). The inhibitory effect of pretreatment with ALP on E-selectin expression was statistically significant for both concentrations of ALP (*p < 0.05).