Oligodeoxynucleotides containing CpG motifs induce IL-12, IL-18 and IFN-gamma production in cells from allergic individuals and inhibit IgE synthesis in vitro.

The effects of phosphorothioate oligonucleotides containing CpG motifs (CpG-ODN) on cultured cells from allergic patients and non-atopic individuals were investigated. In peripheral blood mononuclear cells (PBMC) CpG-ODN led to a significant increase of IFN-gamma. By intracellular cytokine staining, IFN-gamma production could be attributed to NK cells and inhibition experiments indicated an IL-12-dependent mechanism. Moreover, CpG-ODN increased mRNA expression of IL-12 and IL-18 in PBMC. In this respect, no significant difference between allergic and non-atopic individuals was observed. Monocyte-derived dendritic cells were identified as one IL-12- and IL-18-producing source. In addition, stimulation of PBMC derived from atopic patients with CpG-ODN led to a considerable increase of polyclonal IgG and IgM synthesis. In contrast, the production of total IgE was suppressed. CpG-ODN induced a significant rise of IgG and IgM specific for allergens to which the patients were sensitized, whereas allergen-specific IgE levels remained unchanged. Our data suggest that CpG-ODN display a strong influence on the ongoing immune response and might represent potential adjuvants for specific immunotherapy of type I allergy.