title: Distinct pattern of IL-2 and IFN-gamma gene expression in CD4 and CD8 T cells: cytofluorometric analysis at a single cell level using non-radioactive probes.
abstract: IL-2 and IFN-gamma gene expression was analyzed using an original method for in situ hybridization (ISH) with non-isotopic probes and flow cytometric analysis (FC). This method permits rapid detection of mRNA at a single cell level among in vitro activated human peripheral blood mononuclear cells (PBMC) and purified CD4 and CD8 T cell subsets. After stimulation with PMA and ionomycin (PMA+Io), cells were fixed at different times and hybridized with digoxigenin (DIG)-labelled RNA antisense or sense probes specific for IL-2 and IFN-gamma. The level of cytokine gene expression in individual cells was visualized using FITC-conjugated anti-DIG antibodies and the fluorescent signal was analyzed by flow cytometry. Specific hybridization with IL-2 and IFN-gamma antisense probes was detected among activated PBMC within lymphoid cells identified by their light scattering properties. Kinetic analysis of the frequency of mRNA producing cells exhibited a biphasic pattern with an early peak at 6-8 hrs. when percentages of IL-2 and IFN-gamma expressing cells reached 35 +/- 7% and 18 +/- 4%, respectively. Similar data were obtained by enzymatic detection on cell smears using AP-conjugated anti-DIG. Combination of ISH with FC was applied to the comparison of the pattern of cytokine gene expression between CD4 and CD8 T cell subsets isolated by negative selection using immunobeads and magnetic separation. IL-2 was expressed by activated CD8 T cells (25-35%), but CD4 T cells were the major producers of IL-2 as assessed by the high frequency of mRNA expressing cells (60%) and the large amount of mRNA per cell relative to the mean fluorescence intensity. In contrast, IFN-gamma mRNA was preferentially expressed by CD8 T cells (27-37%) and a minority of CD4 T cells (17-23%). Despite quantitative differences, kinetic analysis of IL-2 gene expression in CD4 and CD8 T cells showed similar profiles with an early peak at 6-8 hrs. Upregulation of IL-2 gene expression in CD4 T cells by CD28 co-stimulation increases the amount of IL-2 mRNA per cell as visualized by mean fluorescence intensity. In addition the effect of CD28 co-stimulation on IL-2 mRNA stabilisation was demonstrated by the maintenance of a high frequency of IL-2 expressing CD4 T cells and an elevated level of mRNA per cell for prolonged period after PMA+Io stimulation. By contrast CD28 co-stimulation had no obvious effect on IFN-gamma expression.
authors.affiliation: Faculté de Sciences Médicales et Pharmaceutiques, Laboratoire de Microbiologie-Immunologie Pharmaceutique, Université de Rennes, France.
authors.forename: P Y
authors.initials: PY
authors.lastname: Morvan
authors.forename: C
authors.initials: C
authors.lastname: Picot
authors.forename: R
authors.initials: R
authors.lastname: Dejour
authors.forename: B
authors.initials: B
authors.lastname: Genetet
authors.forename: N
authors.initials: N
authors.lastname: Genetet
mesh_terms: D018106:CD28 Antigens; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D004076:Digoxigenin; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000235:genetics*; D007376:Interleukin-2 / Q000235:genetics*; D015759:Ionomycin / Q000494:pharmacology; D007700:Kinetics; D008213:Lymphocyte Activation; D015347:RNA Probes; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D018106:CD28 Antigens; D007376:Interleukin-2; D015347:RNA Probes; D012333:RNA, Messenger; D015759:Ionomycin; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate; D004076:Digoxigenin