FIG. 5.

The LT-II toxins and CT synergize with proinflammatory stimuli in IL-10 induction. THP-1 cells were pretreated for 1 h with medium only or with 2-μg/ml concentrations of LT-IIa, LT-IIb, or CT. The cells were subsequently incubated for an additional 16 h with medium only, Ec-LPS, Pg-LPS, or FimA. Induction of IL-10 release in culture supernatants was assayed by ELISA. Results are presented as means ± standard deviations of triplicate determinations. Asterisks indicate statistically significant (P < 0.05) enhancement of IL-10 induction compared to treatment with proinflammatory stimuli in the absence of LT-II toxins or CT.