Characterization of the immune response in a new murine model of autoimmune arthritis

Abstract

We have discovered a novel mouse strain that spontaneously develops arthritis, and we are currently assessing its viability as a new model of immune‐mediated arthritis. The purpose of this project was to characterize the immune response in this new strain. Cells of the spleen, lymph nodes, and joints were isolated from AR and non‐AR littermates and analyzed for immune cell proliferation and activation using flow cytometry. Serum was also collected and assayed for immunoglobulin levels and pro‐inflammatory cytokines. AR mice had significantly more immune cells in their joints. The vast majority were neutrophils, although T cells and B cells were also present. Surprisingly, AR mice tended to have lower numbers of total cells isolated from their spleen and lymph nodes, possibly indicating that the immune cells were largely localizing to the joints, the major site of inflammation. The CD4+and CD8+ T cells that were in these organs did show elevated signs of activation in the AR mice (i.e. increased CD25 and CD69 and decreased CD45RB). Mean serum levels of total Ig and IgG1 but not IgG2b were elevated in AR mice. Finally, interleukin‐6 was elevated in all the AR mice in the early stages of disease and tumor necrosis factor‐alpha was elevated in half of the AR mice. Overall, our data indicate that there is more robust inflammatory response occurring in the AR mice.