To 'B' regulated: B cells as members of the regulatory workforce.

Until recently, immune regulation was thought to be predominantly mediated by specialized subsets of T lymphocytes. However, although B lymphocytes have previously been shown to have regulatory properties in autoimmunity, a recent report by Knoechel et al. establishes a role for B lymphocytes in the control of pathogenic autoreactive T cell responses arising when the number of lymphocytes is abnormally low (lymphopenia).