Effect of folate-targeted immunotherapy (FTI) on mice with established collagen-induced arthritis. Mice were immunized with keyhole limpet hemocyanine-fluorescein isothiocyanate (KLH-FITC) in an equal volume of TiterMax Gold adjuvant to generate a high anti-FITC antibody titer. Seven days after arthritis induction, when the average arthritis score had reached 7, mice were treated daily with 600 nmole/kg folate-FITC until day 38. (a) Differences between folate-FITC-treated and untreated mice were easily visualized. (b) Each limb was evaluated weekly by an individual blinded to the treatment groups and was assigned an arthritis score (see Methods and methods). (c) Bone erosion was analyzed on day 49 from radiographs by a radiologist blinded to the treatment groups. (d) Uptake of EC20 in both hind limbs was determined as a measure of activated macrophage accumulation on day 49, represented as percent injected dose of EC20 per gram hind limbs, for instance, %ID EC20/g hind limbs. (e) The change in weight of mice after arthritis induction was measured regularly.