T Cell Activiation by Antigens Flashcards
What is a naive T cell?
mature T cells that left the thymus and are in the lymph nodes and haven’t been exposed to antigens
What is an effector T cell?
A t-cell that went under activation and gained functions to do adaptive immune response
What is CCR7?
chemokine receptor on surface on dendritic cells that allow them to leave the tissue and enter the blood to travel to the lymphatic vesels
How do Dendritic cells end up interacting with CCR7 on the CCR7 receptor?
D.C. TLR interacts with microbe and the D.C displays the antigens on a MHC and also releases TNF alpha and IL-1. the endotherlium cells release chemokines that bind to the chemokine receptor on D.C. cells and allow them to leave the tissue and enter the blood into the lymphatic vessels.
How do naive T-cells circulate the body?
will enter lymph nodes via special vessels (High Endothelial Venules (HEV).
The T cells bind to HEV because naive T cells have CCR7 on them that binds to the adhesion molecules of the HEV.
Where are chemokines made in the lymph nodes?
in the T cells zones
How do D.C and T cells even get to the same area in a lymph node?
CCR7 receptors on both T cells and D.C (made in T cell zones) will be attracted to the chemokines made in this area of the lymph nodes.
What is costimulation?
The TCR of T cells will interact with the MCH/antigen complex on D.C. The costimulator molecule (B7) on D.C. will interact with the costimulatory receptor on T cells (CD28) The D.C got a costimulator molecule when it first saw a PAMP in the tissues
What happens if you have the first costimulatory signal but not the 2nd one?
The T cell dies (apoptosis) or becomes anergic (unresponsive)
Explain the Class II MHC pathway
protein travels to lysosome and is degraded. MHC leaves the E.R and goes to the golgi body and then to the lysosome. travels to surface and recognized by CD4 cells
Explain the Class I MCH pathway
protein enters cytoplasm. bound to ubiquitin. Enters the proteosome and degraded. peptides go to E.R and bind to MHC I there. whole complex goes to the golgi body and then to the surface to be recognized by CD8 cells.
CTLA4
Inhibitory receptor on T-Cells in the lymph nodes that binds to B7 on D.C. (instead of CD28) which causes the T-cells to be anergic/unresponsive
PD-1/PD-1L
PD-1 is an inhibatory molecue on T cells in the tissue. Can interact with PD-1Ligand on tumors or D.C. that cause the T cells to become exhausted
Which types of cells display class II molecules?
dendritic cells, B cells and macrophages
Which types of cells display class I molecules?
all nucleated cells
