title: Age-related differences in phenotype and function of CD4+ T cells are due to a phenotypic shift from naive to memory effector CD4+ T cells.
abstract: Based on the combined expression of CD27 and CD28, a putative model of T cell differentiation has been previously proposed. We used CD27 and CD28 expression in order to comparatively study the size, cytokine production capacity and proliferative response of CD4+ T cell sub-populations from healthy young and elderly volunteers. Elderly persons had a lower percentage of CD27+CD28+ but a higher percentage of CD27-CD28+ and CD27-CD28-CD4+ T cells than the young persons. CD27-CD28-CD4+ T cells were present, although at relatively low numbers, in the vast majority of the healthy elderly donors but were only sporadically detected in young persons. Each CD4+ T cell sub-population exhibited a distinct phenotype and cytokine production profile, which were not affected by age. When purified CD27+CD28+ were stimulated by staphylococcal enterotoxin B, they proliferated to a greater extent than CD27-CD28+ and CD27-CD28-CD4+ T cells. However, we did not observe age-related differences in proliferative response of each sub-population. We concluded that although the size of the different sub-populations differed between the young and the old group, the functional characteristics of each sub-population were the same in both age groups. This suggests that on a per cell basis there is no functional impairment of CD4 memory T cells in elderly persons. Consequently, potential differences in the function of the total CD4+ T cell population are most likely due to different composition of repertoire.
authors.affiliation: Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria.
authors.forename: Rania D
authors.initials: RD
authors.lastname: Kovaiou
authors.forename: Ilka
authors.initials: I
authors.lastname: Weiskirchner
authors.forename: Michael
authors.initials: M
authors.lastname: Keller
authors.forename: Gerald
authors.initials: G
authors.lastname: Pfister
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Cioca
authors.forename: Beatrix
authors.initials: B
authors.lastname: Grubeck-Loebenstein
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology; D018106:CD28 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D004768:Enterotoxins / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology*; D016130:Immunophenotyping; D008875:Middle Aged; D016192:Resting Phase, Cell Cycle / Q000276:immunology; D016615:Telomere / Q000378:metabolism; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D018106:CD28 Antigens; D004768:Enterotoxins; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; C031818:enterotoxin B, staphylococcal