Neutrophils were isolated by Dextran-Ficoll density centrifugation (20, 40). Cell viability was assessed by trypan blue dye exclusion in a hemocytometer and was routinely 96–98% with a purity of over 95%. Neutrophils were directly seeded in 24-well or 96-well plates and allowed to settle for 15 min at 37°C under 5% CO2 prior to further experimentation.