T Cell Activation. Flashcards
What are the 2 signals that can activate a T cell?
Signal 1.
Signal 2.
Where does signal 1 for T cell activation originate from?
A CD3 molecule on a T cell.
How do co-stimulators help with T cell activation?
They induce a response as the binding of a TCR to an MHC is not enough to induce a response on its own.
When are co-stimulatory molecules produced?
When an APC comes into contact with a PAMP or when a T cell binds to an APC or MHC.
What other molecule is produced when a T cell binds to an APC that is bound to a PAMP?
A co-stimulatory molecule.
An MHC bound to a foreign peptide can be described as what?
An APC.
Which interleukin is incredibly important for T cell activation?
IL-2.
What happens to T cells once they have been activated?
They proliferate.
Why is IL-2 needed for co-activation?
It is a safety mechanism that prevents autoimmunity.
What happens if IL-2 is not present during T cell activation?
The T cell cannot enter the cell cycle and replicate.
Is IL-2 necessary for T cell activation?
IL-2 must be present for proliferation to occur.
What happens when signal 1 is activated during T cell activation?
The naive T cell interacts with an MHC via its CD4 molecule.
CD-3 is activated and sends a signal which activates the T cell.
What happens when signal 2 is activated during T cell activation?
Co-stimulatory molecules trigger the T cell to enter G1.
IL-2 is transcribed and proliferation can occur.
What are the 2 types of co-stimulator for T cells?
CD40 ligand.
CD-80/B7.
When will CD-40 ligand and CD-80/B7 be expressed?
In the presence of PAMPs bound to a PRR.
This causes an up-regulation of both co-stimulatory molecules.
