CG sequence- and phosphorothioate backbone modification-dependent activation of the NF-kappaB-responsive gene expression by CpG-oligodeoxynucleotides in human RPMI 8226 B cells.

Oligodeoxynucleotides containing CpG motifs (CpG-ODNs) have gained attention because of their stimulatory effects on innate immune responses. CpG-ODN 1826 containing two GACGTT motifs is well known to activate the mouse immune cells while CpG-ODN 2006 containing three GTCGTT motifs is optimal for human cells. We have shown that stimulation of the human B cell line RPMI 8226 with CpG-ODN 1826 or 2006 results in the activation of IL-8 promoter and nuclear localization of NF-kappaB in the CG sequence- and phosphorothioate backbone modification-dependent manner. It was also demonstrated that myeloid differentiation protein and tumor necrosis factor receptor-associated factor 6 are involved in the signal transduction pathway triggered by the CpG-ODNs. Furthermore, phosphorothioate-modified CpG-ODN 1826 led to induce the NF-kappaB-responsive inflammatory cytokine gene expression in the cells. Experimental results indicated that the phosphorothioate derivative of CpG-ODN 1826 not only activates the mouse immune cells, but also stimulates NF-kappaB responsive gene expression in the human B cell line.