Cytokine levels in control serum and ACS, and in synovial fluid during treatment. Control serum (control), autologous conditioned serum (ACS) and synovial fluid cytokine levels (mean +/- SD) of IL-1RA, TGF-β1, IL-10, IL-6, OSM and OPG during treatment with ACS in 14 OA patients. The large symbols next to the y-axis correspond to the levels of these cytokines in control serum and the injected ACS. TGF-β1 levels in SF were lower than in the injected ACS, and OPG levels in SF were higher than in ACS (P < 0.01). During the course of treatment, no significant changes in cytokine levels occurred despite repeated ACS injection (SF was aspirated before each of the six injections with ACS, at t = 0, Day 3, Day 7, Day 10, Day 14 and Day 21).