Plots of serum cytokine data. Serum cytokines were variably detectable in all cats in the study. Enzyme-linked immunosorbent assay results for serum levels of IL-6 (A), IFN-γ (B), TNF-α (C), and IL-1β (D). Note that one nonresponder showed very high expression of most serum cytokines, indicating a severe systemic proinflammatory state. Abbreviations: IFN, interferon; IL, interleukin; TNF, tumor necrosis factor.