Germinal center reaction in the joints of mice with collagen-induced arthritis - An animal model of lymphocyte activation and differentiation in arthritic joints

Objective. To establish an animal model and provide a basis for investigati ng the role of germinal center (GC) reaction in autoimmune arthritis. Methods. DBA/1 mice were immunized with bovine type II collagen (CII) to el icit collagen-induced arthritis (CIA). Sections of arthritic joints were ex amined by in situ immunohistochemical studies, and purified cells from affe cted joints were subjected to flow cytometry analysis. Results. De novo GC reaction was induced in the arthritic joints of male DB A/1 mice by immunization with bovine CII. In comparison with GCs formed in lymphoid tissues, such as spleen and lymph nodes, we found that these GCs f ormed in the joint tissues of mice with CIA were morphologically typical, a s determined by immunohistologic and flow cytometric assays. Conclusion. The local immune responses in murine CIA induced ectopic GC for mation, as observed in the synovial tissues of patients with rheumatoid art hritis. This system will allow for the first time the direct study of the r ole of the GC reaction in autoimmune arthritis in an animal model.