Granulocyte macrophage-colony stimulating factor (GM-CSF) increases lipopolysaccharide (LPS)-induced IL-6, nitric oxide (NO), and TNF-α production. After pretreating with GM-CSF or leaving untreated for 48 h, microglia were harvested, washed twice, and seeded at 1 × 105 cells/well. Then the cells were treated with varying doses of LPS (0.01 to 1 μg/ml) for 48 h. (A) The expression levels of IL-1β, IL-6, TNF-α and NOS2, mRNA were assessed by quantitative real-time PCR. (B) Concentrations of IL-1β, IL-6, TNF-α , and NO in culture supernatant were analyzed by ELISA and the Griess method. Data indicate mean ± SD. Data are representative of three independent experiments. ***P < 0.001 (GM-CSF pretreated vs. untreated).