Context
Although this paper does not deal specifically with arthritis, its relevance lies in the intriguing speculations it raises on the common basis for autoimmunity and tumor immunity. It suggests that a regulatory T cell controls both tumor specific and self-reactive T cells. Studies show that a subpopulation of CD4+ T cells prevents autoimmune disease in a number of rodent models. Many studies have previously suggested this regulatory T cell population is CD25+ CD4+, and is anergic (non-proliferative) in normal mice. Stimulation of the regulatory T cells suppresses the activation/proliferation of other CD4+ or CD8+ T cells in an antigen non-specific manner. Removal of CD25+ CD4+ T cells elicits autoimmunity, and enhances immune responses to non-self antigens such as allogeneic tissue grafts. Here the authors investigate the hypothesis that removal of CD25+ CD4+ immunoregulatory T cells may evoke immune responses to autologous tumor cells by allowing activation of anti-tumor effector cells. To investigate the role of immunoregulatory CD25+ CD4+T cells in tumor immunity.