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Mem. Inst. Oswaldo Cruz ; 101(4): 437-449, June 2006. graf, tab
Artigo em Inglês | LILACS | ID: lil-435307

RESUMO

The immune mechanisms involved in dengue fever and dengue hemorrhagic/dengue shock syndrome are not well understood. The ex vivo activation status of immune cells during the dengue disease in patients was examined. CD4and CD8 T cells were reduced during the acute phase. Interestingly, CD8 T cells co-expressing activation marker HLA-DR, Q, P, and cytolytic granule protein-Tia-1 were significantly higher in dengue patients than in controls. Detection of adhesion molecules indicated that in dengue patients the majority of T cells (CD4 and CD8) express the activation/memory phenotype, characterized as CD44HIGH and lack the expression of the naïve cell marker, CD62L LOW. Also, the levels of T cells co-expressing ICAM-1 (CD54), VLA-4, and LFA-1 (CD11a) were significantly increased. CD8 T lymphocytes expressed predominantly low levels of anti-apoptotic molecule Bcl-2 in the acute phase, possibly leading to the exhibition of a phenotype of activated/effector cells. Circulating levels of IL-18, TGF-b1 and sICAM-1 were significantly elevated in dengue patients. Early activation events occur during acute dengue infection which might contribute to viral clearance. Differences in expression of adhesion molecules among CD4 and CD8 T cells might underlie the selective extravasation of these subsets from blood circulation into lymphoid organs and/or tissues. In addition, activated CD8 T cells would be more susceptible to apoptosis as shown by the alteration in Bcl-2 expression. Cytokines such as IL-18, TGF-b1, and sICAM-1 may be contributing by either stimulating or suppressing the adaptative immune response, during dengue infection, thereby perhaps establishing a relationship with disease severity.


Assuntos
Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Moléculas de Adesão Celular/imunologia , Citocinas/imunologia , Vírus da Dengue/imunologia , Dengue/imunologia , Linfócitos T/imunologia , Doença Aguda , Antígenos de Diferenciação de Linfócitos T/imunologia , Biomarcadores , Estudos de Casos e Controles , Moléculas de Adesão Celular/metabolismo , Citotoxicidade Imunológica/imunologia , Vírus da Dengue/genética , Leucócitos Mononucleares/imunologia , Ativação Linfocitária/imunologia , Índice de Gravidade de Doença
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