The monoclonal antibody CIICI reacts with the C1 epitope (triple helical position 358-364) of collagen type II. Collagen is a structural protein in bone, cartillage and connective tissue. Collagen type II (CII) is the major collagen of the nucleus pulposa (a component of spine), cartilage and vitreous (a component of the eye). The most commonly used animal model for rheumatoid arthritis (RA) is the collagen-induced arthritis (CIA). Transfer of collagen type II specific monoclonal antibodies induces an acute form of arthritis (collagen type II antibody induced arthritis, CAIA). The monocolonal antibody CIIC1 has been shown to induce CAIA in naïvemice after injection of lipopolysacharide (LPS). However, in combination with the monoclonal antibody M2139, binding to the J1 epitope of CII, the pair of monoclonal antibodies induce arthritis in different strains of mice without any other stimulants. The presence of secondary stimulus, LPS, increases the disease incidence and severity. The monoclonal antibody CIIC1 is cross reactive with rat, bovine, chicken and human CII.