PF-4–induced neutrophil adhesion and exocytosis in the presence of antibodies directed against CD11a, CD18, or L-selectin. Cells were incubated with 2 μmol/L (□) or 10 μmol/L PF-4 (▪) in the presence of the antibodies indicated (10 μg/mL each). Adhesion and exocytosis were determined as described in the legend of Fig 1. Assay backgrounds (adhesion, 11.7% ± 4.5%; exocytosis, 3.7% ± 1.7%) were substracted. Data are given as the mean ± SD of 3 independent experiments.