DC–IFN- and DC–IFN-β have reduced capacity to secrete IL-12.

(A) DC (5 × 10⁴), DC–IFN-α (0.01 ng/mL or 1 ng/mL), or DC–IFN-β (0.01 ng/mL or 1 ng/mL) were cultured with 5 × 10⁵ naive CD4⁺ T cells and immobilized anti-CD3. DC were washed to remove cytokines used for in vitro differentiation. No exogenous cytokines were added to stimulation cultures. Supernatants were harvested after 48 hours of the primary stimulation. The results indicated with * show that p40 IL-12 production was significantly different from control DC p40 IL-12 production (n = 3-4, *P < .05 as determined by paired t test). Results shown are the mean and SEM. (B) DC–IFN-β had reduced capacity to produce p70 IL-12 in response to activation with 0.1% SAC. DC (5 × 10⁴) or DC–IFN-β (1 ng/mL) were cultured with 0.1% SAC. DC were washed to remove cytokines used for in vitro differentiation. No exogenous cytokines were added to stimulation cultures. Supernatants were harvested after 48 hours of stimulation. Results indicated with * show that p70 IL-12 production was significantly different from control DC p70 IL-12 production (n = 3; *P < .05 as determined by paired t test). Results shown are the mean and SEM.