(A) Uptake kinetics of131I-labeled fusion protein and131I-labeled IL-1ra in hind paws of mice with (n = 5) and without CIA (n = 5) after intravenous injection. Data are expressed as mean ± SEM. ** = p < 0.01 versus uptake rates of 131I-labeled IL-1ra in hind paws of arthritic mice or healthy mice and uptake rates of 131I-labeled fusion protein in hind paws of healthy mice. (B) Autoradiogram for the selectively accumulation of the fusion protein in the inflamed joint of mice. (1) and (2), inflamed paw; (3) and (4), normal paw.