IL-2- and CD25-dependent immunoregulatory mechanisms in the homeostasis of T-cell subsets.
IL-2 plays a pivotal role in regulating the adaptive immune system by controlling the survival and proliferation of regulatory T (Treg) cells, which are required for the maintenance of immune tolerance. Moreover, IL-2 is implicated in the differentiation and homeostasis of effector T-cell subsets, including T(H)1, T(H)2, T(H)17, and memory CD8+ T cells. The IL-2 receptor is composed of 3 distinct subunits, namely the alpha (CD25), beta (CD122), and gamma (gammac) chains. Of crucial importance for the delivery of IL-2 signals to Treg cells is the expression of CD25, which, along with CD122 and gammac, confers high affinity binding to IL-2. Notably, recent findings suggest a novel role for CD25, whereby CD25 molecules on Treg cells and possibly other cells are capable of influencing T-cell homeostasis by means of IL-2 deprivation. This review explores these findings and integrates them into our current understanding of T-cell homeostasis.
Division of Immunology and Allergy, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland.
Sven
S
Létourneau
Carsten
C
Krieg
Giuseppe
G
Pantaleo
Onur
O
Boyman
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D006706:Homeostasis; D006801:Humans; D007108:Immune Tolerance; D020381:Interleukin-17 / Q000502:physiology; D007376:Interleukin-2 / Q000276:immunology*; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
D020381:Interleukin-17; D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit