Figure 2.

Thrombin inhibits IL-12 production. PBMC were cultured at a concentration of 10⁶ cells ml⁻¹ in the absence (filled bars) and in the presence of 150 nM thrombin (open bars) for 1 h at 37°C, then supplemented with FCS (1%) in the presence of different activators: PHA (5 μg ml⁻¹), LPS (0.1 μg ml⁻¹) and anti-CD3 (0.1 μg ml⁻¹)/anti-CD28 (1 μg ml⁻¹). After 16 h of incubation, cell-free supernatants were obtained and IL-12 present in the supernatants were determined by ELISA. The means±s.e.m. of three independent experiments are presented. Asterisks indicate statistically significant (P<0.05) differences between IL-12 release in cultures treated with thrombin versus untreated, as determined using Student's t-test. In the absence of the activators, levels of IL-12 were undetectable.