FIG. 2.

LT-II toxins and CT regulate cytokine induction in activated cells. 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, E. coli LPS (Ec-LPS), P. gingivalis LPS (Pg-LPS), or FimA. Culture supernatants were assayed for TNF-α (A) or IL-1β (B) responses by ELISA. Results are shown as means ± standard deviations of triplicate determinations. Asterisks indicate statistically significant (P < 0.05) inhibition of TNF-α (A) or enhancement of IL-1β (B) responses in LPS- or FimA-activated cells by the toxins.