Fig 2. Effects of various metal ions on the LPS-induced production of IL-6 and TNF-α in RAW264 cells.

RAW264 cells were incubated for 8 h in medium containing LPS (1 μg/ml) (A, B, and C), poly(I:C) (50 μg/ml) (D), or zymosan A (500 μg/ml) (E) in the presence or absence of NiCl₂ or NiSO₄ at the indicated concentrations, or 300 μM of NiCl₂, CoCl₂, ZnCl₂, or PdCl₂ (B and C). The concentrations of IL-6 and TNF-α in the medium were determined by ELISA and cell viability was determined by the MTT assay. The mean value of the control was set to 1.0 (C). Data represent the mean ± S.E.M. (n = 3, 4). **p < 0.01 between the indicated groups. Data are representative of three independent experiments.