Locally produced complement fragments C5a and C3a provide both costimulatory and survival signals to naive CD4+ T cells.
Immunity
; 28(3): 425-35, 2008 Mar.
Article
em En
| MEDLINE
| ID: mdl-18328742
ABSTRACT
Costimulatory signals are critical to T cell activation, but how their effects are mediated remains incompletely characterized. Here, we demonstrate that locally produced C5a and C3a anaphylatoxins interacting with their G protein-coupled receptors (GPCRs), C5aR and C3aR, on APCs and T cells both upstream and downstream of CD28 and CD40L signaling are integrally involved in T cell proliferation and differentiation. Disabling these interactions reduced MHC class II and costimulatory-molecule expression and dramatically diminished T cell responses. Importantly, impaired T cell activation by Cd80-/-Cd86-/- and Cd40-/- APCs was reconstituted by added C5a or C3a. C5aR and C3aR mediated their effects via PI-3 kinase-gamma-dependent AKT phosphorylation, providing a link between GPCR signaling, CD28 costimulation, and T cell survival. These local paracrine and autocrine interactions thus operate constitutively in naive T cells to maintain viability, and their amplification by cognate APC partners thus is critical to T cell costimulation.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ativação Linfocitária
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Linfócitos T CD4-Positivos
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Complemento C3a
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Complemento C5a
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Sobrevivência Celular
Limite:
Animals
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article