Inhibition of ⁵⁹Fe uptake in J774 macrophages by IFN-γ/LPS stimulation. Macrophages were incubated overnight with the indicated concentrations of IFN-γ (U/mL), LPS (ng/mL), and/or NMMA (500 μmol/L) and then exposed to 50 μg/mL ⁵⁹Fe-Tf for 8 hours. Nitrite production was assayed in the culture medium by the Griess reaction. Results are expressed as percent inhibition of iron uptake compared with the control, and are representative of 5 separate experiments. Values are given as the mean ± SE of triplicate cultures. Versus control: *P < .01, **P < .001, ***P < .0001; versus IFN/LPS: ^#P< .001.