Keeping It Brief

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Science  26 Jan 2007:
Vol. 315, Issue 5811, pp. 438-439
DOI: 10.1126/science.315.5811.438d

The cytokine interleukin-2 (IL-2) is both produced by and exerts strong effects on T cells. Despite its fundamental importance for T cell development and immune regulation, IL-2 is only fleetingly expressed, consistent with a need to keep the potent effects of this growth factor under tight control.

Villarino et al. have investigated the management of IL-2 expression by helper T (TH) cells and find that several feedback mechanisms exist to ensure the brevity of its expression. Selection cytokines—including some that use receptors bearing the common γ chain—exhibited the ability to suppress IL-2 expression. Most potent among these was IL-2 itself, and it was at its best in combination with one or more of the other cytokines. Negative feedback was also mediated by the intracellular STAT family of transcription factors, which assist with the differentiation of TH1 and TH2 cells. These in vitro observations were supported by in vivo experiments, in which treatment of mice with recombinant IL-2 measurably reduced the levels of IL-2 produced after immunization. It will be of interest to investigate whether these pathways cooperate in distinct ways to control early T cell immunity, regulatory T cells, and the formation of T cell memory. — SJS

J. Exp. Med. 10.1084/jem.20061198 (2007).

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