RESUMO
Double-positive (DP) CD4(+) CD8(+) T cells normally represent a thymic subpopulation that is developed in the thymus as a precursor of CD4(+) or CD8(+) single-positive T cells. Recent evidence has shown that DP cells with an activated phenotype can be tracked in secondary lymph organs. The detection of an activated DP population in the periphery, a population that expresses T cell receptors unselected during thymic negative selection in murine models of Trypanosoma cruzi infection and in humans with Chagas disease, raise new questions about the relevance of this population in the pathogenesis of this major parasitic disease and its possible link with immunoendocrine alterations.
Assuntos
Doença de Chagas/imunologia , Subpopulações de Linfócitos T/imunologia , Animais , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Doença de Chagas/fisiopatologia , Sulfato de Desidroepiandrosterona/imunologia , Modelos Animais de Doenças , Glândulas Endócrinas/imunologia , Humanos , Hidrocortisona/imunologia , Ativação Linfocitária , Camundongos , Receptores de Antígenos de Linfócitos T/metabolismoRESUMO
Ageing of the endocrine system (endocrinosenescence) has been closely related to immunosenescence. Dehydroepiandrosterone sulphate (DHEAS), a steroid hormone produced by the adrenals with reported enhancing immunomodulatory properties, consistently decline during ageing in parallel to detrimental increase in peripheral glucocorticoids. We investigated here the adjuvant effects of DHEAS during intraperitoneal immunization to Mycobacterium tuberculosis heat shock protein 70 (mycHSP70) in old (24 months) as well as young (3 months) BALB/c mice. Both young and old mice had significantly higher Immunoglobulin G (IgG) levels following immunization. Young mice co-immunized with mycHSP70-DHEAS presented an early increase in specific IgG levels and showed increased Interferon-gamma production compared to old mice. Also, T cells of immunized young animals were consistently more resistant to the immunosuppressive effects of glucocorticoids and to DHEAS. DHEAS was not effective in modulating antigen-specific T-cell proliferation, Interleukin-2 production or percentage of recent activated T-cell subsets (CD4 + CD69 + and CD8 + CD69 +). Our data further indicate mycHSP70 as a putative good antigen in vaccine to tuberculosis. Our data also suggest that DHEAS produced adjuvant effects upon humoral and some cellular immune responses of young, but not old mice and indicate that immunization with DHEAS is capable of changing T-cell responses to steroids.
Assuntos
Adjuvantes Imunológicos , Envelhecimento/imunologia , Proteínas de Bactérias/imunologia , Sulfato de Desidroepiandrosterona/imunologia , Proteínas de Choque Térmico HSP70/imunologia , Imunoglobulina G/sangue , Interferon gama/metabolismo , Linfócitos T/imunologia , Vacinas contra a Tuberculose/imunologia , Adjuvantes Imunológicos/farmacologia , Animais , Formação de Anticorpos , Antígenos CD/análise , Células Cultivadas , Corticosterona/imunologia , Sulfato de Desidroepiandrosterona/farmacologia , Dexametasona/imunologia , Relação Dose-Resposta a Droga , Feminino , Imunidade Celular , Interleucina-2/metabolismo , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos BALB C , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismo , Fatores de Tempo , VacinaçãoRESUMO
Para avaliar o efeito da atividade física regular na imunosenescência, comparou-se parâmetros imunológicos de 20 idosos corredores aos de 20 idosos sedentários e 10 jovens sedentários. Os idosos corredores apresentaram resposta proliferativa de linfócitos T a OKT-3 e produção de interleucina-2 maiores do que os idosos sedentários, porém similares aos jovens. Eles apresentaram produção de interleucina-3 menor, mas também semelhante aos jovens. A interleucina-6 sérica deles foi menor do que a dos idosos sedentários. Conclui-se que a prática regular de atividade física por longos anos tem o potencial de desacelerar a imunosenescência / To access the effect of regular physical activity on immunosenescence, the immunological parameters of 20 elderly runners were compared to those of 20 elderly sedentary persons and 10 sedentary young persons. The running elderly subjects presented a higher T lymphocyte proliferative response to OKT-3 and a higher interleukin-2 production than elderly sedentary subjects, but similar to that of young subjects, plus a lower production of interleukin-3, but also similar to that of young subjects. Their serum interleukin-6 was lower than that of sedentary elderly subjects. We conclude that practicing regular physical activity for many years has the potential to decelerate immunosenescence...