T cells climb on board Blimp-1

B lymphocyte-induced maturation protein (Blimp)-1, a transcriptional repressor, has long been known to drive the terminal maturation of B cells into plasma cells. However, two recent studies reveal an unanticipated role for Blimp-1 in T-cell homeostasis. Blimp-1-deficient T cells exhibit enhanced proliferative and functional responses following activation, and induce spontaneous colitis. Hence, aside from its role in B-cell differentiation, Blimp-1 directs restraint among T cells.