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1.
J Immunol ; 191(3): 1300-6, 2013 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-23817410

RESUMEN

γδ T cells represent a subset of unconventional T lymphocytes that are known for their reactivity against different pathogens and considered as intermediate mediators between adaptive and innate immunity. We provide in this paper further insights underlying the changes that affect the γδ T cell compartment with advanced age in humans. We show that both aging and CMV infection impact independently on the γδ T cell compartment. Most γδ T cells are significantly affected by age and present a decreased frequency in the elderly. The decline of the γδ T cell pool appears to be independent from the activity of the thymus, arguing in favor of an extrathymic site of γδ T cell production in humans. Of note, CMV infection, which is directly associated with the activation of the pool of Vδ2(-) γδ T cells, promotes nonetheless the inflation of this compartment throughout life. CMV seropositivity accentuates further the accumulation of highly differentiated lymphocytes in Vδ2(-) γδ T cell subsets with time, in contrast to Vδ2(+) γδ T cells, which maintain a less differentiated phenotype. This is similar to the effect of CMV on αß T cells and suggests that γδ T cells may vary in differentiation phenotype according to distinct stimuli or pathogens.


Asunto(s)
Infecciones por Citomegalovirus/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Subgrupos de Linfocitos T/inmunología , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Citomegalovirus/inmunología , Citotoxicidad Inmunológica/inmunología , Humanos , Activación de Linfocitos/inmunología , Recuento de Linfocitos , Persona de Mediana Edad , Timo/inmunología
2.
J Immunol ; 189(12): 5541-8, 2012 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-23136199

RESUMEN

Reduced thymopoiesis and continuous mobilization of naive T cells into the effector-memory pool can lead to severe alterations of the naive T cell compartment. However, maintenance of the naive T cell population is essential to mount effective immune responses. Evidence of homeostatic regulation of naive T cells is currently debated in animal models. In humans, the situation remains unresolved, in particular with advanced age. In this study, we analyzed the CD4(+) and CD8(+) naive T cell compartments from elderly, young adults thymectomized during early childhood, and HIV-1-infected patients, which are characterized by T lymphocytopenia. We show a direct association between increased turnover and decreased frequency of naive T cells. Moreover, the IL-7-induced pathway was fully functional in naive T cells from elderly and young adults thymectomized during early childhood, who are characterized by elevated IL-7 plasma levels. Our findings support the establishment of homeostatic regulation of naive T cell proliferation in humans. This regulation is particularly active in lymphopenic hosts, such as elderly and thymectomized patients.


Asunto(s)
Diferenciación Celular/inmunología , Homeostasis/inmunología , Linfopenia/patología , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Timectomía , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Memoria Inmunológica/inmunología , Masculino , Persona de Mediana Edad , Subgrupos de Linfocitos T/patología , Adulto Joven
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