Collagen-induced arthritis (CIA) in mice is widely used as an experimental model for rheumatoid arthritis (RA) in humans. CIA is mediated by autoantibodies, which bind to a particular region of type II collagen, such as CB11 (CNBR-digested fragment of type II collagen) (Terato et al, 1985). Antibody-mediated CIA can be induced by i.v. injection of a combination of four different monoclonal antibodies generated by the ArthroMAB mouse B-hybridoma cell lines. T In the mouse CIA model, the antibody response that is correlated with arthritis is mainly associated with binding to the epitopes of C11b, J1 and U1. This cocktail of 4 purified mouse monoclonal antibodies bind to the well-defined epitopes C11b, J1, D3 and U1, which are spread over the entire CII (CB8, CB10 and CB11 fragments), possibly encouraging better immune complex formation on the cartilage surface for the initiation of arthritis (Terato et al, 1985).