Rapamycin decreases autoantibody production. MRL-lpr mice were randomized to treatment with rapamycin, MMF, or control. Retro-orbital bleeds were obtained every 2 weeks to measure mouse anti-dsDNA IgG-specific antibodies in sera by quantitative ELISA. Mice treated with rapamycin had a statistically significant decrease in average titer levels compared with MMF (0.3 μg/mL vs 5 μg/mL; P < .001) and control (0.3 μg/mL vs 8 μg/mL; P = .001) after 4 weeks of treatment. Figure 6 depicts results of antibody titers for each mouse over time with 4 mice in each treatment group. Results are normalized to titer at initation of treatment for each mouse. Error bars represent SEM.