FIG. 2.

Pneumolysin is a strong inducer of IL-1α, IL-1β, and IL-18 production. Peritoneal macrophages were left unstimulated (M), treated with cholesterol only (C), or stimulated with rPLY, cholesterol-treated rPLY (CT-rPLY), or LPS at a concentration of 0.1 μg/ml (white bars) or 1 μg/ml (black bars) for 24 h, and culture supernatants were then collected. The levels of cytokines in supernatants were determined by ELISA. The results are representative of three similar experiments. The data are the means ± standard deviations for three determinations.