Effects of aspirin, NaS, and acetaminophen on aggregation. Neutrophils were incubated for 10 min in the absence or presence of ASA (□), NaS (○), or acetaminophen (▵), followed by stimulation with FMLP (A), AA (B), or PMA (C) for 2 min and measurement of aggregation. Results are expressed as percent of stimulated aggregation in the absence of inhibitor and are the means ± SEM of three experiments.