Metal fractionation constant indicates that Cd is preferentially absorbed by synoviocytes.

<p>K<sub>D</sub> = (Me/<sup>70</sup>Zn) <sub>cells</sub>/(Me/<sup>70</sup>Zn) <sub>medium</sub> (where Me = metal) was calculated at 120h after addition of Cu, Cd, In, Pb, Au, Sn, Bi and ultra-trace amounts of <sup>70</sup>Zn in cultures of OA or RA synoviocytes, treated (striped bars) or not (normal bars) with IL-17 and TNF-α. At equilibrium, K<sub>D</sub> = 1. Black lines represent the high affinity group, while white bars the low affinity group. Data are the mean of at least three independent experiments.</p>