Time course of C5a-induced IL-8 secretion from PBMC. Approximately 0.5 × 10⁶ freshly prepared PBMC were incubated in the presence (▪) or the absence (▴) of 200 nmol/L of human C5a for different lengths of time (0 to 4 hours). The cells were then removed and the supernatants were taken for measurement of secreted IL-8 by ELISA. Results shown are the mean ± SE from three separate measurements, each in duplicates.