Abstract
We designed class I/II hybrid inhibitory oligodeoxynucleotides (iODNs), called iSG, and found that the sequence 5′‐TTAGGG‐3′, which has a six‐base loop head structure, and a 3′‐oligo (dG)3–5 tail sequence are important for potent immunosuppressive activity. Interestingly, splenocytes isolated from ovalbumin (OVA)‐immunized mice and treated with iSG3 showed suppression of not only interleukin (IL)‐6, IL‐12p35, IL‐12p40, and interferon (IFN) γ mRNA expression, but also IL‐4 and IL‐13 mRNA expression. Thus, both Th2 and Th1 immune responses can be strongly suppressed by iODNs in splenocytes from allergen‐immunized mice, suggesting usefulness in the treatment of diseases induced by over‐active immune activation.