Altered B cell development and anergy in the absence of Foxp3.

The importance of regulatory T cells in immune tolerance is illustrated by the human immune dysregulatory disorder IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked), caused by a lack of regulatory T cells due to decreased or absent expression of Foxp3. Although the majority of work on regulatory T cells has focused on their ability to suppress T cell responses, the development of significant autoantibody titers in patients with IPEX suggests that regulatory T cells also contribute to the suppression of autoreactive B cells. Using a murine model, deficient in the expression of Foxp3, we show that B cell development is significantly altered in the absence of regulatory T cells. Furthermore, we identify a loss of B cell anergy as a likely mechanism to explain the production of autoantibodies that occurs in the absence of regulatory T cells. Our results suggest that regulatory T cells, by either direct or indirect mechanisms, modulate B cell development and anergy.