Figure 4. Fe uptake by T lymphocytes and hepatocytes correlates with [Fe₃Cit₃].

(A) Speciation plots for Fe-citrate species were calculated for Fe∶citrate ratios from 1∶100–200∶100 using the Hyperquad simulation and speciation (HySS) program. Predicted relative abundance (%) of the two most common Fe-citrate species, at pH 7.4, is marked by a blue vertical line and a red (Fe₃Cit₃) or blue (FeCit₂) dot. (B) Fe uptake by T lymphocytes and hepatocytes incubated with different iron∶citrate ratios increases with the relative abundance of Fe₃Cit₃. Experiments were performed at least three times with three replicates per experiment. Each point represents the mean (n = 3) ±1SD. (C) Regression analysis showing a significant correlation between Fe uptake by CD3⁺ (left) and HepG2 (right) cells with predicted [Fe₃Cit₃] concentration at pH 7.4.