| Research Abstract |
IL-18 has been shown to be a strong co-factor for Th1 T cell development. However, we previously demonstrated that when IL-18 was combined with IL-2, there was a synergistic induction of a Th2 cytokine, IL-13, in both T and NK cells (T.Hoshino, J.Immunol. 162 : 5070, 1999). More recently, we and other groups have reported IL-18 can potentially induce IgE, IgG1 and Th2 cytokine production in murine experimental models (T.Hoshino, Eur. J.Immunol. 30 : 1998, 2000).
Here we report on the generation of IL-18 transgenic (Tg) mice in which mouse mature IL-18 cDNA fused to the signal peptide of the mouse Ig κ-chain was expressed. CD8^+ CD44^<high> T cells and macrophages were increased, but B cells were decreased in these mice while serum IgE, IgG1, IL-4 and IFN-γ levels were significantly increased. Splenic T cells in IL-18 Tg mice produced higher levels of IFN-γ, IL-4, IL-5 and IL-13 than control wild type mice. Thus, aberrant expression of IL-18 in vivo results in the increased production of both Th1 and Th2 cytokines.
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