title: Surface and intracellular interleukin-2 receptor expression on various resting and activated populations involved in cell-mediated immunity in human peripheral blood.
abstract: The kinetics of assembly of the high-affinity interleukin-2 receptor (IL-2R)alpha/beta/gamma were investigated by studying intracellular and surface expression of IL-2Ralpha, beta and gamma by T cells, monocytes and natural killer (NK) cells. IL-2Ralpha and IL-2Rgamma were expressed by small numbers of resting T cells. These numbers increased following stimulation, to maximal expression at 48 h and 72 h, respectively. This observation was consistent with de novo synthesis of the receptor protein in response to the stimulus. The proportion of T cells producing IL-2Rbeta was smaller and up-regulated later than the proportion of cells producing IL-2Ralpha or IL-2Rgamma. IL-2Rbeta may therefore slow the assembly of the high-affinity IL-2R on T cells. A small number of resting NK cells expressed IL-2Ralpha, both on the cell surface and intracellularly, but this increased over 72 h on stimulated NK cells. IL-2Rbeta was constitutively expressed, both on the cell surface and intracellularly, by monocytes and NK cells. An increased proportion of NK cells and monocytes produced IL-2Rbeta, 24 h and 4 h post-stimulation, respectively. Maximal or plateau expression occurred at 72 h and 24 h post-stimulation, for NK cells and monocytes, respectively. The early up-regulation of intracellular IL-2Rbeta for monocytes may facilitate the up-regulation of surface IL-2Rbeta, and early assembly of the high-affinity IL-2R, accelerating monocyte activation and function. High constitutive intracellular IL-2Rgamma expression (> 80%) in all types of leucocyte investigated, decreased over the 72 h following stimulation with a concurrent increase in surface expression. IL-2Rgamma was expressed by increased proportions of T cells, monocytes and NK cells, 4 h following stimulation. The intracellular storage of IL-2Rgamma may accelerate translocation to the cell surface after stimulation. The early translocation of IL-2Rgamma may reflect its usage as a signal transduction molecule by other cytokine receptors - IL-4, IL-7, IL-9 and IL-15. This study delineated the potential expression of the high-affinity IL-2Ralpha/beta/gamma on various stimulated leucocytes. The differential kinetics of assembly of the high-affinity IL-2Ralpha/beta/gamma on different leucocyte subsets suggests that IL-2 may regulate the inflammatory cellular responses in a sequential manner, paralleling the timed expression of IL-2Ralpha/beta/gamma on the monocytes, NK cells and T cells.
authors.affiliation: University of South Australia, Adelaide, South Australia; Haematology Department, Women's and Children's Hospital, Adelaide, South Australia.
authors.forename: S
authors.initials: S
authors.lastname: Hodge
authors.forename: G
authors.initials: G
authors.lastname: Hodge
authors.forename: R
authors.initials: R
authors.lastname: Flower
authors.forename: P
authors.initials: P
authors.lastname: Han
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal; D017252:CD3 Complex / Q000097:blood; D019002:CD56 Antigen / Q000097:blood; D002462:Cell Membrane / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology; D007700:Kinetics; D007962:Leukocytes / Q000276:immunology*; D018950:Lipopolysaccharide Receptors / Q000097:blood; D008213:Lymphocyte Activation; D009000:Monocytes / Q000276:immunology; D015375:Receptors, Interleukin-2 / Q000097:blood*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D019002:CD56 Antigen; D018950:Lipopolysaccharide Receptors; D015375:Receptors, Interleukin-2