IFN-γ, IL-18, nitrites, and TNF-α levels return to normal in As₂O₃-treated MRL/lpr mice. Four-month-old MRL^+/+ (white bars) and MRL/lpr (gray bars) mice had been treated daily with PBS or As₂O₃ (5 μg/g) for 2 months. ELISAs were used to determine their serum IFN-γ (A), IL-18 (B), and TNF-α (C) concentrations, and Griess reagents to measure their serum nitrite concentrations (D). Black squares represent data from individual animals and bars correspond to the mean for 6 to 9 mice per group.