RESUMO
The binding of a T cell to an APC results in T cell actin cytoskeletal rearrangement leading to the formation of an immunological synapse. The APC cytoskeleton has been thought to play a passive role in this process. In this study, we demonstrate that dendritic cells (DC), unlike other APC, actively polarize their actin cytoskeleton during interaction with T cells. DC cytoskeletal rearrangement was critical for both the clustering and the activation of resting T cells. This study provides compelling evidence that the APC cytoskeleton plays an active role in the immunological synapse and may explain the unique ability of DC to activate resting T cells.
Assuntos
Comunicação Celular/imunologia , Citoesqueleto/imunologia , Células Dendríticas/citologia , Células Dendríticas/imunologia , Actinas/antagonistas & inibidores , Actinas/imunologia , Actinas/metabolismo , Animais , Agregação Celular/efeitos dos fármacos , Agregação Celular/imunologia , Comunicação Celular/efeitos dos fármacos , Polaridade Celular/efeitos dos fármacos , Polaridade Celular/imunologia , Células Cultivadas , Técnicas de Cocultura , Citocalasina D/farmacologia , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/metabolismo , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Interfase/imunologia , Ativação Linfocitária/efeitos dos fármacos , Teste de Cultura Mista de Linfócitos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismoRESUMO
Maturation of dendritic cells (DC) is critical to their development into potent APCs. Upon maturation, DC up-regulate the expression of MHC class II as well as costimulatory and adhesion molecules, all of which are important in Ag presentation. In addition, they undergo structural changes characterized by the expression of numerous long dendrites. Fascin is an actin-bundling protein that has been reported to be important for the development of dendrites. In this study, we evaluated fascin expression and function during DC maturation into potent APC. In vitro, treatment of bone marrow-derived DC (BM-DC) with GM-CSF resulted in increased levels of fascin expression. This increase correlated directly with an increase in MHC class II and B7-2 expression. Fascin expression was decreased by the addition of TGF-ss and increased by the addition TNF-alpha to the culture. These cytokines suppress or enhance DC maturation, respectively. Increased levels of fascin expression were found to correlate with increased APC activity in a one-way MLR. Specific inhibition of fascin expression, using antisense oligonucleotides, markedly reduced this APC allostimulatory activity. These data demonstrate that fascin expression correlates with DC maturation into APC, and it plays a significant role in the ability of DC to function as APC. This observation is the first evidence linking fascin-mediated dendrite formation with the APC activity of DC.
