Lec 13: Space Time and TcR Flashcards
How long does it take immune cells to recirculate in the body
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Where do key cell-to-cell interactions take place
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What signals are involved in cell-to-cell interactions
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Where do effector cells go and how do they get there1
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Read Qi er al 2014
spatiotemporal basis of innate and adaptive immunity in secondary lymphoid tissue
also rewatch the lecture videos
Intravital microscopy
microscopy technique used to observe biological systems in vivo
real time analysis of cell cell interactions
How do lymphocytes exit the blood, and enter the lymphnodes
via HEV = hihg-endothelial venules
HEVs express ligands for L-selectin adhesion molecules
L-selectin is expressed on naive lymphocytes
contact allows the cells to slow down and roll along the vessel walls
further interactions with other adhesion molecules stop the cells and allow them to squeeze through the junctions between the cells
CCR7
is essential for T cell homing to the lymph nodes
S1PR1
sensitivity to S1PR1 recruits T cells back to circulation
HEV
HIgh endothelial venule
T cell - DC interactions under homeostatic conditions
during their meandering migration through the lymph node, T cells have several dynamic interactions with DCs
CD will interact with over 5000 t cells. hr
Lymphocyte migration along fibroblast reticular cells (FRCs)
lymphocytes are guided in their lymph node migration by a 3D network consisting of FRCs on which DCs also reside, thus promoting T cell-DC interactions
FRC network surrounds the HEVs and naive T cell exit from HEVs through openings directly onto the FRC-DC network
HEVs also accommodates newly arriving migratory DCs from peripheral sites
Four key steps of immune cell extravasation from the vasculature into tissues
Rolling
activation
arrest/adhesion
transmigration
Naive lymphocytes are activated in the secondary lymphoid tissue
- > inflammatory chemokines guide T cell migration in the lymph node
- > DCs are essential for the activaiton of naive T cells
- > Requirement of CD4+ T cells in effective memory CD8+ T cell priming
roles of cognate antigen during CD4+ T cells effective memory priming of CD8+ T cells
CD8+ T cells show changes in their migrational pattern in the presence of antigen specific CD4+ T cells interacting with stimulatory DCs
CD8+ T cells migrated more rapidly towards DCs associated with an antigen-specific CD4+ T cell, interacitng with these relevant DCs five to eight times more often than with equidistant irrelevant DCs