Immune Netw.  2011 Feb;11(1):1-10. 10.4110/in.2011.11.1.1.

Seeing Is Believing: Illuminating the Source of In Vivo Interleukin-7

• Kim GY
• Hong C
• Park JH

• KMID: 2150689
• DOI: http://doi.org/10.4110/in.2011.11.1.1

Abstract

Interleukin-7 (IL-7) is an essential cytokine for T cells. However, IL-7 is not produced by T cells themselves such that T cells are dependent on extrinsic IL-7. In fact, in the absence of IL-7, T cell development in the thymus as well as survival of naive T cells in the periphery is severely impaired. Furthermore, modulating IL-7 availability in vivo either by genetic means or other experimental approaches determines the size, composition and function of the T cell pool. Consequently, understanding IL-7 expression is critical for understanding T cell immunity. Until most recently, however, the spatiotemporal expression of in vivo IL-7 has remained obscured. Shortage of such information was partly due to scarce expression of IL-7 itself but mainly due to the lack of adequate reagents to monitor IL-7 expression in vivo. This situation dramatically changed with a recent rush of four independent studies that describe the generation and characterization of IL-7 reporter mice, all utilizing bacterial artificial chromosome transgene technology. The emerging consensus of these studies confirmed thymic stromal cells as the major producers of IL-7 but also identified IL-7 reporter activities in various peripheral tissues including skin, intestine and lymph nodes. Strikingly, developmental and environmental cues actively modulated IL-7 reporter activities in vivo suggesting that IL-7 regulation might be a new mechanism of shaping T cell development and homeostasis. Collectively, the availability of these new tools opens up new venues to assess unanswered questions in IL-7 biology in T cells and beyond.

Keyword

Thymus; T cells; Homeostasis; Bacterial artificial chromosome

MeSH Terms

Animals
Biology
Chromosomes, Artificial, Bacterial
Consensus
Cues
Homeostasis
Indicators and Reagents
Interleukin-7
Intestines
Lymph Nodes
Mice
Organothiophosphorus Compounds
Skin
Stromal Cells
T-Lymphocytes
Thymus Gland
Transgenes
Indicators and Reagents
Interleukin-7
Organothiophosphorus Compounds