title: Androgens contribute to age-associated changes in peripheral T-cell homeostasis acting in a thymus-independent way.
abstract: OBJECTIVE
  Considering a causal role of androgens in thymic involution, age-related remodeling of peripheral T-cell compartments in the absence of testicular hormones was evaluated.
  
  
  METHODS
  Rats were orchidectomized (ORX) at the age of 1 month, and T-peripheral blood lymphocytes (PBLs) and splenocytes from young (75-day-old) and aged (24-month-old) rats were examined for differentiation/activation and immunoregulatory marker expression.
  
  
  RESULTS
  In ORX rats, following the initial rise, the counts of CD4+ and CD8+ PBLs diminished with aging. This reflected the decline in thymic export as shown by recent thymic emigrant (RTE) enumeration. Orchidectomy increased the count of both of the major T-splenocyte subsets in young rats, and they (differently from controls) remained stable with aging. The CD4+:CD8+ T-splenocyte ratio in ORX rats shifted towards CD4+ cells compared to age-matched controls. Although in the major T-cell subsets in the blood and spleen from aged ORX rats the numbers of RTEs were comparable to the corresponding values in age-matched controls, the numbers of mature naïve and memory/activated cells substantially differed. Compared with age-matched controls, in aged ORX rats the numbers of CD4+ mature naïve PBLs and splenocytes were reduced, whereas those of CD4+ memory/activated cells (predictive of early mortality) were increased. Additionally, in spleens from aged ORX rats, despite unaltered thymic export, CD4+CD25+FoxP3+ and natural killer T cell counts were greater than in age-matched controls.
  
  
  CONCLUSIONS
  (i) Age-related decline in thymopoietic efficacy is not dependent on androgen presence, and (ii) androgens are involved in the maintenance of peripheral T-cell (particularly CD4+ cell) homeostasis during aging.
authors: Department of Microbiology and Immunology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia.
authors: Nevena
authors: N
authors: Arsenović-Ranin
authors: Duško
authors: D
authors: Kosec
authors: Ivan
authors: I
authors: Pilipović
authors: Biljana
authors: B
authors: Bufan
authors: Zorica
authors: Z
authors: Stojić-Vukanić
authors: Katarina
authors: K
authors: Radojević
authors: Mirjana
authors: M
authors: Nacka-Aleksić
authors: Gordana
authors: G
authors: Leposavić
mesh_terms: D000375:Aging / Q000276:immunology*; D000728:Androgens / Q000276:immunology*; D000818:Animals; D002469:Cell Separation; D005434:Flow Cytometry; D006706:Homeostasis / Q000276:immunology*; D008297:Male; D009919:Orchiectomy; D051381:Rats; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
chemical_list: D000728:Androgens