Deletion of a coordinate regulator of type 2 cytokine expression in
Mechanisms underlying the differentiation of stable T helper subsets will be important in understanding how discrete types of immunity develop in response to different pathogens. An evolutionarily conserved ~;400 base pair non-coding sequence in the IL-4/IL-13 intergenic region, designated CNS-1, was deleted in mice. The capacity to develop Th2 cells was compromised in vitro and in vivo in the absence of CNS-1. Despite the profound effect in T cells, mast cells from CNS-1-deleted mice maintained their capacity to produce IL-4. A T cell-specific element critical for optimal expression of type 2 cytokines may represent evolution of a regulatory sequence exploited by adaptive immunity.