Expression of IFN-γ induced by CpG-DNA stimulation in a human myeloid leukemia cell line KG-1

Abstract

CpG-DNA has potent immunostimulatory effects to induce expression of cytokines and chemokines in macrophages, dendritic cells, and B cells. KG-1 is a human myeloid leukemia cell line used as an in vitro model system for dendritic cell differentiation. Here, we investigated effect of CpG-DNA on IFN-γ expression in KG-1 cells. Based on the mRNA and protein expression, stimulation of KG-1 cells with the phosphorothioated form of CpG-DNA induced expression of IFN-γ. The IFN-γ promoter includes one NF-κB binding site and two AP-1 binding sites. Induction of IFN-γ was markedly reduced in the presence of NF-κB, p38, and MEK1 inhibitors. Furthermore, AP-1 was found to interact with both of the two binding sites in the IFN-γ promoter. Therefore, we conclude that CpG-DNA induced activation of NF-κB and AP-1 leads to induction of IFN-γ, which may further contribute to immunostimulatory activity of CpG-DNA.