Inhibition of PMN superoxide production and degranulation by C2-ceramide.
PMNs were suspended in buffer containing cytochrome C with or without superoxide dismutase (panel A only). PMNs were incubated with C2-ceramide, dihydro-C2-ceramide (control lipid), or buffer for 30 minutes at 22°C. PMNs were then primed with 50 ng/mL G-CSF for 10 minutes at 37°C. FMLP (1 μM) was added, and samples were incubated at 37°C for an additional 5 minutes, then placed on ice. PMNs were removed by centrifugation. (A) Superoxide present in the supernatants was determined by spectroscopic measurement of cytochrome C reduction. (B-C) The markers of specific and tertiary granule release, lactoferrin and gelatinase respectively, were measured in the supernatants by ELISA. Data represent the mean ± SEM of at least 3 experiments. *Significantly different from control;P < .05.
