Antiarthritic effect of human alpha 1 antitrypsin (hAAT) in collagen induced arthritis (CIA) model. Human AAT (Prolastin®) was intraperitoneally injected in DBA/1 mice (n = 9), twice per week starting 6 days before until day 70 after CII immunization. Control group received saline injections (n = 7) (A) Serum hAAT protein levels in DBA/1 mice were measured by ELISA (mean+SD). ↓ indicates the day of first hAAT injection. (B) Serum anti-hAAT antibody levels (anti-hAAT-IgG) in DBA/1 mice were measured by ELISA. Each dot represents antibody levels (day 49 after bCII immunization, arbitrary units) of an individual mouse. (C) Arthritis score. For each paw, 0 is normal and 4 is the most severe arthritis. The maximum score for each animal is 16. Each line represents the scores from hAAT treated group (open triangles, mean-SD) or control group (open circles, mean+SD, *p = 0.029 by AUC analysis) (D) Incidence of severe arthritis is defined by arthritic score/mouse > 3 (**p = 0.0025 by logrank test). Dotted line, saline injected control group; Solid line, hAAT treated group.