title: Increased apoptosis of CD45RO- T cells with aging.
abstract: Increasing susceptibility to infectious and autoimmune phenomena have long been recognized to accompany advancing age in otherwise healthy individuals. Recently animal models of aging have suggested that age-associated immune dysfunction may correlate with defects in T cell apoptosis. We have examined activation-induced apoptosis defects in human peripheral T cells from young individuals (mean age = 31 +/- 3 years old) compared to aged individuals (mean age = 67 +/- 8 years old). Following in vitro activation of T cells with PHA and IL-2, apoptosis was measured in T cell subsets using 7-amino actinomycin D (7-AAD) staining and analysis via three colour flow cytometry. There was no significant difference in apoptosis of the total CD3+ T cell population at early and late time points. Interestingly, increased apoptosis in the CD3+ CD45RO- T cell population of older adults was observed by culture day 6. While the total number of CD3+ CD45RO- cells was not different between young (< 33 years) and old (> 65 years) individuals, 32% of these cells did not undergo apoptosis in younger individuals while only 10% of these cells avoided this fate in older individuals. These results suggest that accumulation of CD45RO+ T cells may occur in aged subjects due in part to preferential elimination of CD45RO- cells with activation. Furthermore, as new or continued immune response requires differentiation of CD45RO+ T cells to CD45RO+ T cells after activation, increased apoptosis instead of survival in aged individuals could lead to observed T cell immune deficiency.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham 35294-0007, USA.
authors.forename: F J
authors.initials: FJ
authors.lastname: Herndon
authors.forename: H C
authors.initials: HC
authors.lastname: Hsu
authors.forename: J D
authors.initials: JD
authors.lastname: Mountz
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D017209:Apoptosis; D017252:CD3 Complex / Q000276:immunology*; D003609:Dactinomycin / Q000031:analogs & derivatives / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D017493:Leukocyte Common Antigens / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D017252:CD3 Complex; D005456:Fluorescent Dyes; D003609:Dactinomycin; C025942:7-aminoactinomycin D; D017493:Leukocyte Common Antigens