Induction of Interleukin-6 and Interleukin-12 in Bovine B Lymphocytes,Monocytes,and Macrophages by a CpG Oligodeoxynucleotide (ODN 2059) Containing the GTCGTT Motif

Abstract

Bacterial DNA and synthetic oligodeoxynucleotides (ODN) that contain unmethylated CpG dinucleotides flanked by certain bases (CpG ODN) have been shown to activate murine and human B cells and to induce proinflammatory cytokines by monocytes/macrophages and dendritic cells (DC). However, the CpG ODN sequences optimal for mice and humans are different. In the current study, the effects of CpG ODN, which were defined to stimulate strong responses in either mouse or human leukocytes, were compared for stimulation of bovine B lymphocyte proliferation and macrophage cytokine mRNA expression. The optimal CpG ODN was then tested for induction of cytokines in peripheral blood mononuclear cells (PBMC) and purified B lymphocytes, monocytes, and macrophages. At a high ODN concentration (40 μM), all but two CpG ODN tested stimulated B cell proliferation, which was dependent on unmethylated CpG motifs. CpG ODN 2059 containing the GTCGTT motif shown to activate human leukocytes also promoted the highest level of bovine B cell proliferation at a lower concentration (10 μM) when compared with CpG ODN containing AACGTT or GACGTT motifs active for murine leukocytes. Furthermore, ODN 2059 induced interleukin-6 (IL-6) production by B lymphocytes and IL-6 and IL-12 production by PBMC, monocytes, and macrophages. In contrast, IL-1β and tumor necrosis factor-α (TNF-α) production was either very low or undetectable. Consistent with increased IL-12 production, ODN 2059 also stimulated interferon-γ (IFN-γ) production by PBMC. Importantly, the levels of cytokines induced by ODN 2059 were comparable to those generated in response to Escherichia coli DNA. The weak TNF-α response combined with the vigorous IL-6 and IL-12 response to ODN 2059 indicate the potential use of this CpG ODN as an adjuvant to enhance both antibody-mediated and IFN-γ-mediated macrophage activation, which are important for protection against disease caused by intracellular pathogens of cattle.