Spleen cells were harvested from IOE-infected IL-18Rα-/- and WT mice on day 7 p.i., in vitro stimulated with IOE Ags and the frequency of IOE-specific CD8+T cells as well as TNF-α producing CD8+T cells was analyzed by flow cytometry. A, Contour plot shows the percentage of CD3+CD8+ T cells in naive, IOE-infected WT, and IL-18Rα-/- mice. B, CD8+ T cells were gated and analyzed for intracellular TNF-α production, naive mice have less than 1% of TNF-α-producing CD8+ T cells, infected WT mice have a higher percentage of TNF-α-producing CD8+ T cells than IOE infected IL-18Rα-/-. C, The absolute number of TNF-α-producing CD8+ T cells in the three groups of mice. The data shown are from a representative mouse from each group (n=3). The data shown are from one experiment that is representative of three different experiments. ***P < 0.001.