SAC-activated DC direct Th1 development from naive Th cells through the release of IL-12. Naive Th cells were activated by SEA presented by autologous DC. DC were or were not activated with SAC and endogenous IL-12 production was or was not neutralized with anti-IL-12 (αIL-12). Th cells were cultured for 14 days, the last 7 days in the presence of rIL-2 and restimulated with CD3 and CD28 MoAb. Supernatants were procured after 24 hours and levels of IL-4 and IFN-γ were analyzed. Results are shown as duplicate points representing two independent primary cultures treated under identical conditions in the same experiment. Data are representative of three independent experiments.