Biological Activity Determination of Recombinant Equine Interleukin-18 and Identification of Neutralized Activity of Monoclonal Antibodies

To examine the bioactivity of recombinant equine interleukin-18 (rEIL-18) obtained from Escherichia coli, rEIL-18 was evaluated to see if it showed a synergistic effect with recombinant human interleukin-12 (rhIL-12) for the induction of equine interfer-on-γ (EIFN-γ ) gene expression from equine peripheral blood mononuclear cells (PBMCs) by Real-time RT-PCR. REIL-18 could in- duce EIFN-γ mRNA expression from equine PBMCs about 20-fold higher than that of negative control in the presence of rhIL-12. And the effect to induce EIFN-γ gene expression was dose-dependent with rEIL-18 in a fixed concentration of rhIL-12. Nine an-ti-rEIL-18 monoclonal antibodies (mAbs) were also evaluated if they could neutralize the bioactivity of rEIL-18. And one of the 9 mAbs could neutralize rEIL-18 bioactivity and its effect was dose-dependent.