We found that in the brains of lupus mice, IFN-γ–regulated genes are highly expressed, IFN-γ induces neurons to secrete CCL8 via JAK/STAT1 signaling, and microglia are activated and show increased phagocytosis following entry of IFN-γ into the brain. The gene discussed is STAT1; the disease is systemic lupus erythematosus.