A positive feedback loop of IL-21 signaling provoked by homeostatic CD4+CD25- T cell expansion is essential for the development of arthritis in autoimmune K/BxN mice.

Rheumatoid arthritis is a joint-specific autoimmune inflammatory disease of unknown etiology. The K/BxN mouse is a model of rheumatoid arthritis that is thought to be mainly due to autoantibody-mediated inflammatory responses. We showed previously that homeostatic proliferation of autoreactive CD4(+) T cells is required for disease initiation in the K/BxN mice.

Prevention of spontaneous arthritis by inhibiting homeostatic expansion of autoreactive CD4+ T cells in the K/BxN mouse model.

Objective: K/BxN-transgenic mice are a model of autoimmune arthritis, similar to rheumatoid arthritis. This study was undertaken to determine whether inhibition of lymphopenia-provoked homeostatic expansion can prevent spontaneous development of disease in the K/BxN model.

Methods: To inhibit homeostatic expansion of autoreactive T cells, K/BxN mice with disease in the preclinical stage were adoptively transferred with CD4+ T cells purified from nontransgenic BxN or Thy1.