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

KD = (Me/70Zn) cells/(Me/70Zn) medium (where Me = metal) was calculated at 120h after addition of Cu, Cd, In, Pb, Au, Sn, Bi and ultra-trace amounts of 70Zn in cultures of OA or RA synoviocytes, treated (striped bars) or not (normal bars) with IL-17 and TNF-α. At equilibrium, KD = 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.