In vivo targeting of the small immunoprotein F8 and the fusion protein F8-IL10 in arthritic mice. (a) Near infrared fluorescence imaging. Arthritic mice (n = 3) were injected with small immunoprotein (SIP) (F8)-Alexa750. Near infrared fluorescence imaging analysis was performed 24 hours after injection. Arrows indicate grade 2 swelling in the front paws of the mice. (b to c) Phosphorimaging. Arthritic mice (n = 2) were injected (b) intravenously with 125I-labelled SIP(F8) or (c) subcutaneously with 125I-labelled F8-IL10. Uptake of radio-iodinated antibodies was analyzed by phosphorimaging 24 hours after injection. The ranges of lesion to nonaffected paw ratios measured by phosphorimaging were 7.4 to 13.9 for SIP(F8) intravenously and 5.0 to 6.8 for F8-IL10 subcutaneously.