The role of PI3Kδ in supporting neutrophil-endothelial cell interactions in vivo. (A) Percent reduction in neutrophil accumulation on HUVECs pretreated with IC87114 (2 μM) one hour prior to stimulation with TNFα. Results are expressed as the percentage of cells that bound to vehicle (0.3% DMSO)-treated endothelial cell substrate at wall shear rates of 100 and 300 s^-1. The requirement for E-selectin is demonstrated by the ability of the function-blocking mAb CL3 to inhibit neutrophil attachment to cytokine-stimulated endothelium at a wall shear rate of 300 s^-1. TNFα-stimulated HUVEC substrate was also incubated with IC87114 (2 μM for 15 minutes) to assess the ability of IC87114 to directly inhibit selectin-ligand interactions (^*). All data represent the mean ± SD of 3 sets of experiments performed in duplicate. (B) Percent inhibition in attachment of human neutrophils that were pretreated with IC87114 (2 μM) to TNFα-activated HUVECs at a wall shear rate of 300 s^-1. Results are expressed as the percentage of vehicle (0.3% DMSO)-treated cells that bound to cytokine-stimulated endothelium. (C) Attachment of WT versus p110δ-deficient neutrophils (with and without prior incubation with IC87114) to resting or TNFα-activated bend3.1 cells at a wall shear rate of 100 s^-1. Results (A-C) represent the mean ± SD for 3 experiments performed in triplicate.