title: Serum from aged F344 rats conditions the activation of young macrophages.
abstract: There is considerable controversy about the molecular mechanisms responsible for the variations in innate immunity associated with age. While in vivo, aged animals and humans react to an inflammatory signal with an excessive production of pro-inflammatory cytokines, studies in vitro generally show that this response is attenuated in macrophages from old individuals. In an effort to examine possible extrinsic factors that might affect the response of macrophages to lipopolysaccharide (LPS), we have challenged peritoneal macrophages obtained from young rats with sera obtained from rats of different ages. Our results indicate that the serum from aged rats significantly impairs the capacity of young macrophages to induce tumor necrosis factor-alpha (TNF-alpha) production, while at the same time it increases the basal levels of interleukin-6 (IL-6). The effect of serum from aged donors on TNF-alpha secretion requires pre-incubation and is sensitive to heat inactivation. In contrast, the stimulating effect on IL-6 is resistant to heat, and thus should not be due to a protein factor. Therefore, our results indicate that the age-related changes in macrophage activity are not only the consequence of intrinsic changes, but there also appears to be a modulatory effect imparted by the external milieu.
authors.affiliation: Instituto de Ciencias Biomédicas, Programas de Biología Celular y Molecular, and Inmunología, Facultad de Medicina, Universidad de Chile, Independencia 1027, Santiago, Chile.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Gómez
authors.forename: Claudio
authors.initials: C
authors.lastname: Acuña-Castillo
authors.forename: Sumiyo
authors.initials: S
authors.lastname: Nishimura
authors.forename: Viviana
authors.initials: V
authors.lastname: Pérez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Escobar
authors.forename: Flavio
authors.initials: F
authors.lastname: Salazar-Onfray
authors.forename: Valeria
authors.initials: V
authors.lastname: Sabaj
authors.forename: Claudio
authors.initials: C
authors.lastname: Torres
authors.forename: Robin
authors.initials: R
authors.lastname: Walter
authors.forename: Felipe
authors.initials: F
authors.lastname: Sierra
mesh_terms: D000375:Aging / Q000097:blood / Q000276:immunology*; D000818:Animals; D002478:Cells, Cultured; D015850:Interleukin-6 / Q000097:blood / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000187:drug effects / Q000276:immunology*; D008264:Macrophages / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000276:immunology*
chemical_list: D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha