APP promotes nitrite accumulation (a) and TNF-α production (b) in the culture supernatants of LPS-activated RAW 264.7 macrophages. RAW 264.7 macrophages were activated using LPS (1 μg/ml) and APP (0–80 μg/ml) for 20 h. The nitrite concentrations were determined from the Griess reaction (21), and the levels of TNF-α were measured using sandwich ELISA. Results are expressed as means ± SE; n=3. The points at APP concentrations between 2.5 and 20 μg/ml differ significantly (p