This study was performed to provide insight for the optimization and regulation of immune homeostasis, which should be taken into account in the development of cell therapy using DCs and/or cytokine. Human CBDCs costimulated with LPS and IL-12 were examined for cytokine expression compared with ABDCs. Our results showed that costimulation with IL-12 and LPS in CBDCs resulted in increased expression of IL-23. Concomitantly, the phosphorylation of ERKs and p38 MAPK was increased, suggesting that these kinases are important signaling components for IL-23 induction in CBDC costimulated with LPS and IL-12. Furthermore, production of IL-23 in CBDC costimulated with LPS and IL-12 caused CD4(+)CD45RO(+) memory cells to increase IFN-gamma production. Taken together, CBDCs, costimulated with LPS and IL-12, show a synergistic increase in IL-23 production via enhanced phosphorylation of ERK1/2 and p38 MAPK and consequently, an induction of IFN-gamma production in the memory cells.