title: IL-7 concentration is increased in nonagenarians but is not associated with markers of T cell immunosenescence.
abstract: Interleukin-7 is a homeostatic cytokine that contributes to the maintenance of the T cell pool. It also has proinflammatory effects and is involved in the pathogenesis of autoimmune diseases. Due to its homeostatic effects, IL-7 has been proposed as a potential rejuvenation factor for the elderly immune system. We analyzed the correlation of plasma IL-7 concentrations and the proportions of different T cell populations in nonagenarians (n=163) participating in the Vitality 90+ study. Young individuals (n=35, aged 19-30years) were used as controls. The numbers of CD3+, CD14+, CD4+ and CD8+ cells and the expression of the CD28 costimulatory molecule on CD4+ and CD8+ lymphocyte subsets were analyzed using flow cytometry. The plasma IL-7 levels were significantly higher in the nonagenarians compared to the controls (7.86 vs. 5.74pg/ml, p=0.004). In the nonagenarians, plasma IL-7 levels correlated inversely with the proportion of CD3+ T cells and directly with the proportion of CD14+ monocytes and plasma C-reactive protein. No correlation was observed between plasma IL-7 levels and the proportions of CD4+CD28- or CD8+CD28- subsets. These results suggest that the IL-7 levels in nonagenarians do not have an inhibitory effect on the development of immunosenescence; rather they are associated with increased inflammation.
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, University of Tampere, Finland. saara.marttila@uta.fi
authors.forename: Saara
authors.initials: S
authors.lastname: Marttila
authors.forename: Juulia
authors.initials: J
authors.lastname: Jylhävä
authors.forename: Marko
authors.initials: M
authors.lastname: Pesu
authors.forename: Sanna
authors.initials: S
authors.lastname: Hämäläinen
authors.forename: Marja
authors.initials: M
authors.lastname: Jylhä
authors.forename: Antti
authors.initials: A
authors.lastname: Hervonen
authors.forename: Mikko
authors.initials: M
authors.lastname: Hurme
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D015551:Autoimmunity; D015415:Biomarkers / Q000097:blood; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D016922:Cellular Senescence / Q000235:genetics / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007156:Immunologic Memory / Q000235:genetics* / Q000276:immunology; D007249:Inflammation / Q000276:immunology; D015851:Interleukin-7 / Q000097:blood*; D018950:Lipopolysaccharide Receptors / Q000276:immunology; D018655:Lymphocyte Count; D008297:Male; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015415:Biomarkers; D017252:CD3 Complex; D015851:Interleukin-7; D018950:Lipopolysaccharide Receptors