Multifocal structure of the T cell - dendritic cell synapse.
The structure of immunological synapses formed between murine naive T cells and mature dendritic cells has been subjected to a quantitative analysis. Immunofluorescence images of synapses formed in the absence of antigen show a diffuse synaptic accumulation of CD3 and LFA-1. In electron microscopy, these antigen-free synapses present a number of tight appositions (cleft size approximately 15 nm), all along the synapse. These tight appositions cover a significantly larger surface fraction of antigen-dependent synapses. In immunofluorescence, antigen-dependent synapses show multiple patches of CD3 and LFA-1 with a variable overlap. A similar distribution is observed for PKCtheta and talin. A concentric organization characteristic of prototypical synapses is rarely observed, even when dendritic cells are paralyzed by cytoskeletal poisons. In T-DC synapses, the interaction surface is composed of several tens of submicronic contact spots, with no large-scale segregation of CD3 and LFA-1. As a comparison, in T-B synapses, a central cluster of CD3 is frequently observed by immunofluorescence, and electron microscopy reveals a central tight apposition. Our data show that it is inappropriate to consider the concentric structure as a "mature synapse" and multifocal structures as immature.
Brossard
Cédric
C
Département de Biologie Cellulaire, Institut Cochin, INSERM U567, CNRS UMR 8104, Université René Descartes, Paris, France.
Feuillet
Vincent
V
Schmitt
Alain
A
Randriamampita
Clotilde
C
Romao
Maryse
M
Raposo
Graça
G
Trautmann
Alain
A
D000818:Animals; D017252:CD3 Complex / Q000032:analysis; D003599:Cytoskeleton / Q000502:physiology; D003713:Dendritic Cells / Q000648:ultrastructure*; D005455:Fluorescent Antibody Technique; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D016169:Lymphocyte Function-Associated Antigen-1 / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D013569:Synapses / Q000648:ultrastructure*; D013601:T-Lymphocytes / Q000648:ultrastructure*
D017252:CD3 Complex; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1