CpG motifs present in bacteria DNA rapidly induce lymphocytes to secrete interleukin 6, interleukin 12, and interferon gamma.

TLDR

Bacterial infection triggers a rapid inflammatory response, partly driven by a 6‑base CpG motif that is 20‑fold more common in bacterial DNA and activates B cells. The CpG motif rapidly induces coordinated secretion of IL‑6, IL‑12, and IFN‑γ from B, T, and NK cells, outperforming lipopolysaccharide and contributing to innate cytokine and antibody responses.

Abstract

Bacterial infection stimulates the host to mount a rapid inflammatory response. A 6-base DNA motif consisting of an unmethylated CpG dinucleotide flanked by two 5' purines and two 3' pyrimidines was shown to contribute to this response by inducing polygonal B-cell activation. This stimulatory motif is 20 times more common in the DNA of bacteria than higher vertebrates. The current work shows that the same motif induces the rapid and coordinated secretion of interleukin (IL) 6, IL-12, and interferon gamma (but not IL-2, IL-3, IL-4, IL-5, or IL-10) in vivo and in vitro. Stimulatory CpG DNA motifs induced B, T, and natural killer cells to secrete cytokine more effectively than did lipopolysaccharide. Thus, immune recognition of bacterial DNA may contribute to the cytokine, as well as the antibody production characteristic of an innate inflammatory response.