Generation of neutralizing mouse anti-mouse IL-18 antibodies for inhibition of inflammatory responses in vivo

Abstract

The proinflammatory cytokine IL-18 mediates IFN-γ production as well as the induction of Th1 polarized immune responses in synergy with IL-12. In this study, we describe the production of isogeneic monoclonal antibodies (Mabs) directed against murine IL-18 (mIL-18). Immunization of IL-18-deficient mice with recombinant mIL-18 in the presence of CpG-oligodeoxynucleotides (CpG-ODN) and alum as adjuvant resulted in high anti-IL-18 serum titers. We could identify two Mabs, SK721-2 and SK113AE-4, which were able to bind to IL-18 and neutralize its IFN-γ inducing effect in vitro with an IC 50 of 40–100 ng/ml. In vivo, LPS-induced IFN-γ production was reduced by 60–85% following a single administration of Mabs SK113AE-4 or SK721-2. Since IL-18 is likely to be involved in the pathogenesis of inflammatory diseases such as rheumatoid arthritis or Crohn's disease, neutralizing mouse anti-mouse IL-18 Mabs have the potential to become valuable tools for the therapeutic exploration of long-term IL-18 blockade in vivo.