Impaired Th1 response induced by LV-transduced DCs. We analyzed T helper function by using DC:T cell co-culture and IL-4 and IFN-γICCS. Immature DCs were infected with mock (293T supernatants) or LV on d5 and treated with LPS and TNFα. The DCs were harvested and co-cultured with naïve CD4+ T cells at a DC:T cell ratio of 1:10. On Day 7 amd 9 after co-culture, the cells were re-stimulated and the T helper cell populations were examined by INF-γ and IL-4 antibody ICCS as described in the Materials and Methods. The percentages of cell populations are indicated in the FACS quadrants. The results are representative of four independent experiments.