title: Prevalence of CD8+ T-cell expansions in relation to age in healthy individuals.
abstract: Clonal CD8+ T-cell expansions have been identified in the peripheral blood of healthy adults and occasionally in children. These expansions are often large, yet their etiology is unknown. This study evaluated the relationship between age and the prevalence of these expansions in a healthy population (n = 147) aged 9 months to 85 years. Expansions were determined using immunofluorescence staining with monoclonal antibodies to different T-cell receptor (TCR)-variable regions. The overall prevalence was 13.6% and increased linearly with age as follows: 0% for 9-month-olds, 2.7% for 4- to 12-year-olds, 13.3% for 20- to 30-year-olds, 20.7% for 35- to 50-year-olds, and 33.4% for 65- to 85-year-olds. Multiple expansions were observed only in the oldest group. Certain TCR-variable regions appeared to be preferentially utilized by these expansions, which suggests a response to a particular antigenic stimulus. Childhood illness and vaccination histories did not provide insight into the etiology of these expansions. Age was the only measured factor that was associated with these expansions.
authors.affiliation: Department of Medicine, National Jewish Medical and Research Center, Denver, Colorado, USA.
authors.forename: N S
authors.initials: NS
authors.lastname: Ricalton
authors.forename: C
authors.initials: C
authors.lastname: Roberton
authors.forename: J M
authors.initials: JM
authors.lastname: Norris
authors.forename: M
authors.initials: M
authors.lastname: Rewers
authors.forename: R F
authors.initials: RF
authors.lastname: Hamman
authors.forename: B L
authors.initials: BL
authors.lastname: Kotzin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D001424:Bacterial Infections / Q000276:immunology; D018791:CD4 Lymphocyte Count; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003710:Demography; D005260:Female; D006801:Humans; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D012016:Reference Values; D012727:Sex Characteristics; D012959:Socioeconomic Factors; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014777:Virus Diseases / Q000276:immunology
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta