Expression of the IL-2 receptor gamma subunit in resting human CD4 T lymphocytes: mRNA is constitutively transcribed and the protein stored as an intracellular component.
IL-2 receptor (IL-2R) is composed of three subunits named IL-2R alpha, IL-2R gamma. Here, we study the expression of the IL-2R gamma in highly purified, resting peripheral human CD4 T lymphocytes. We show by FACS analysis that the IL-2R gamma subunit is not detectable at the cell surface of peripheral CD4 T lymphocytes. This result has been verified after acid treatment of the cell surface and analysis with three specific anti-IL-2R gamma mAb. Using RT-PCR and intracellular FACS analysis, we demonstrate that IL-2R gamma is constitutively expressed at the mRNA level and the protein is stored as an intracellular component in resting CD4 T lymphocytes. IL-2R alpha and beta subunits are not detectable by these methods. In addition, we show that CD4 T cell remain insensitive to a variety of cytokines that share IL-2R gamma as a common subunit of their receptors (e.g. IL-2, IL-4, IL-7 and IL-15). The kinetics of cell surface expression of IL-2R gamma have been studied after activation of CD4 T lymphocytes and compared with induction of IL-2R alpha and IL-2R beta. Maximum expression of IL-2R gamma is observed after 2 days of stimulation, and remains constant and comparable to IL-2R beta up to day 5. We conclude from these studies that IL-2R gamma is translocated to the membrane only after T cell activation and induction of the IL-2R alpha and IL-2R beta genes. We hypothesize that in CD4 T cells a large intracellular pool of IL-2R gamma is present but that its cell surface translocation depends on the expression of alpha and/or beta chains specific for IL-2, IL-4, IL-7, IL-9 or IL-15.
Bani
L
L
Unité d'Immunogénétique Cellulaire, Institut Pasteur, France.
David
D
D
Moreau
J L
JL
Cayota
A
A
Nakarai
T
T
Ritz
J
J
Thèze
J
J
D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D006801:Humans; D007399:Interphase / Q000276:immunology; D007424:Intracellular Fluid / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis*; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics*
D008565:Membrane Proteins; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2