Effect of metal chelators on ascorbate-induced DHR oxidation. Samples of sera from healthy subjects (CTRL), hemochromatotic (HH), or thalassemic (THAL) patients were assayed for DHR oxidation as described in “Materials and methods” in the presence of the iron-specific chelators desferrioxamine (DFO), L1, and apo-transferrin (aTf), as well as the general metal chelator DTPA. The concentrations of the chelators refer to their final concentrations after addition of the DHR reagent. DHR oxidation is given as in Figure 1.