Collagen-Induced Arthritis (CIA) in mice is one of the most commonly used animal models of autoimmune arthritis. Disease is induced in susceptible strains by immunization with heterologous collagen type II (CII) in adjuvant. CIA in mice carries both the pathology driven by T cells and the antibody production against collagen. Disease is induced with one injection of CII in complete Freund´s adjuvant (CFA). A booster injection containing collagen in Incomplete Freund´s adjuvant (IFA) is given day 21 to enhance disease development. CIA is dependent on genetic factors but also environmental factors determine the severity of the disease.

Onset of arthritis is observed shortly after boost day 21. The mice develop an acute nonsymmetrical erosive polyarthritis. Both Th1 and Th17 cells play important roles in the disease but Th17 cells appear to play the dominant pathological role. Both B and T cell immunity to autologous CII is requried for disease manifestation.