FIG. 1.

Cytokine induction by the LT-II toxins and CT. THP-1 cells were incubated for 16 h in the absence or presence of heat-labile enterotoxins (LT-IIa, LT-IIb, and CT; all at 2 μg/ml) or with E. coli LPS (10 ng/ml; positive control). Culture supernatants were assayed for cytokine content by ELISA. Results are presented as means ± standard deviations of triplicate determinations. Values that are statistically significantly different (P < 0.05) from those of controls treated only with medium are indicated by an asterisk.