P-selectin and PAF/IL-8 cooperatively activate αMβ2. (A) Neutrophils were incubated in the absence (control) or presence of P-selectin Ig chimera (P-sel Ig), PAF, PAF plus P-selectin Ig chimera, IL-8, and IL-8 plus P-selectin Ig chimera. Samples were then transferred to the wells immobilized with fibrinogen and cell adhesion was measured. The results are expressed as the mean ± SD values of the adherent cells determined in triplicate measurements of 3 separate experiments. (B) Neutrophils were incubated without (control) or with PAF, IL-8, and PMA followed by staining with mAb IB4 or CBRM1/5 and Alexa Fluor 488–conjugated goat antibody to mouse IgG for flow cytometric analysis. Results were the representative of 3 independent experiments. (C-D) Neutrophils were treated without (control) or with PAF or PAF plus P-selectin Ig chimera (C), or IL-8 (D) and stained with mAb IB4 and Alexa Fluor 488–conjugated goat antibody to mouse IgG. They were then processed for confocal laser scanning microscopy. Neutrophils were stained with mAb IB4 for the representative images (top panels) and their intensities of fluorescent particles (means ± SDs; bottom panels). The differences between control and PAF were statistically insignificant (P > .05), whereas the differences between PAF plus P-sel Ig or IL-8 and control were statistically significant (P < .01).