MIIM - Ocular Defences: The Immune System III - Week 4 Flashcards
Is the MHC marker and peptide recognition by a T cell alone enough to activate it?
No
Which cell is the best antigen presenting cell?
Dendritic cell
In non-inflamed tissue, how efficient are dendritic cells at capturing antigens and stimulating naïve T cells?
Highly efficient at capturing antigens but poor stimulators of naïve T cells.
Do dendritic cells have a high or low level of MHCII on their plasma membrane?
Low
What is secreted by dendritic cells?
TGF-β
Can dendritic cells migrate easily to lymph nodes?
No, its restricted
What initiates dendritic cell maturation, and what is it essential for?
Initiated when it binds pathogens.
Essential for naïve T cell activation.
Name 6 maturation events for dendritic cells.
Migration of the cell to draining lymphoid tissue
Increased antigen processing
Increased MHCI and MHCII expression
Increased surface espression of adhesin
Expression of co-stimulatory molecules
Secretion of cytokines
Do maturing dendritic cells gain or lose capacity to capture antigens?
Lose
Name the three molcules involved in the best characterised co-stimulatory signal.
CD80 and CD86 on the surface of the APC, and CD28 which is found on all T cells.
Define signal 1.
The antigen specific recognition by a T cell
Define signal 2.
A co-stimulatory signal needed in addition to signal 1, given by mature dendritic cells.
Define signal 3.
Secretion of selected cytokines by the mature antigen presenting cell that has successfully activated and costimulated a naïve T cell.
Once a naïve CD4 T cell receives signals 1 and 2, what does it express (2) and secrete? What else?
It expresses CD40L and IL-2R.
It secretes IL-2 and now proliferates.
What happens to a CD4 T cell with signal 3?
It differentiates, and performs its effector function.