Figure 2

Interleukin (IL)-7 increases joint damage and inflammation in collagen-induced arthritis. Mice were injected with either phosphate-buffered saline (PBS) or IL-7. Radiographs of the ankle joints were taken at day 33. Radiologic joint damage was graded for each ankle with a scoring index from 0 to 3. (A) Representative radiographs show an unaffected control (nonarthritic) ankle joint, and space narrowing, variability in bone density, and roughened bone surface in an arthritic ankle joint (arrows). IL-7 significantly increased radiologic damage as compared with that in the PBS group (mean scores of 1.2 ± 0.1 versus 1.6 ± 0.2, respectively (B). Consistent with the radiograph scores, histologic examination of the ankles showed significantly increased severity of inflammation, bone and cartilage erosions, and periosteal exostosis with IL-7 treatment compared with PBS (C). Values are expressed as mean ± SEM of 15 mice per group (scores of two ankles per mouse were averaged); statistical differences with PBS group of *P < 0.05, **P < 0.01, and ***P < 0.005.