Figure 6.

CIITA siRNA enhanced IL-4 production in Th1 cells. (a, b, c) Culture supernatants of the Th1 and Th2 cells restimulated with anti-CD3 plus anti-CD28 were collected and the cytokines levels were determined by ELISA. The results show that CIITA siRNA (CIITA si)-transfected Th1 cells produced substantial levels of IL-4 compared to controls, while expression of IFN-γ and IL-2 were basically not changed. On the other hand, decreased levels of CIITA did not significantly alter cytokine expression patterns in Th2 cells. (d) The levels of histone acetylation in the IL-4 promoter of Th1 and Th2 cells were determined by ChIP assay. The acetylated histone H3 of IL-4 promoter was significantly increased in CIITA si-treated Th1 cells, but not in the relevant Th2 cells.