In vitro effects of exogenous Cu upon IFN-γ production in healthy controls. Mononuclear cells from normal donors were incubated for 48 h in the absence or presence of anti-CD3 (200 ng/ml), Cu (10 μM CuCl2) or both. Bars represent mean (+/-SEM) IFN-γ concentration in supernatants from six different donors. Unstimulated cells or cells stimulated with Cu alone did not produce IFN-γ. *p < 0.05 vs. anti-CD3-stimulated cells (Wilcoxon signed rank test).