Introduction to the Immune System 5 Flashcards
What are T cells derived from?
derive from common lymphoid progenitor (in bone marrow) but migrate to the thymus for majority of their development.
Once matured what do T cells do?
They enter the bloodstream and migrate to secondary lymphoid organs
Where does the majority of the maturation of T cells occur?
In the thymus
What do immature T cells acquire in the thymus?
There own specific antigen receptor which will be unique to that T cell
Where do mature naive T cells travel?
They keep recirculating from lymphoid to lymphoid anti, they encounter their complimentary receptor
What happens when a naive T cell encounters is complimentary antigen?
The T cell becomes activated and undergoes the final stage of differentiation to become an effector T cell
These cells proliferate and differentiate into effector cells
What is the function of a T cell?
To recognise and bind to antigens
How to T cells bind and recognise antigens?
Via a specific antigen receptor
What is the T cell receptor made up of?
Consist of 2 polypeptide chains, α and β, linked by a disulphide bond.
Similar to a single Fab fragment of antibody, has one antigen binding site.
Which family do T cell receptors being to?
members of the immunoglobulin superfamily
T cells can only recognise antigens when…
it is complexed in an MHC not just on its own
Other than T cell receptors what the molecules do all T cells present?
CD3
What does CD3 complex with?
Our T cell receptors to send signals into the cells
Does CD3 actually bind to antigens?
NO it only recognises when an antigen is bound to the T cell
Which molecule is specific to cytotoxic T cells?
CD8
What is the main function of cytotoxic T cells?
Kill virus infected cells or malignant cells
Which molecule is specific to T helper cells?
CD4
What is the main function of T helper cells?
They increase macrophage function
They provide help to the B cells for antibody production
How are T cell receptors generated?
In a similar process to B cells
Uses recombinant activates gene (RAG) proteins to perform V(D)J somatic recombination.
Guided by 12/23 RSS rule.
Describe the structure of T cell receptors
2 polypeptide chains, α and β, linked by a disulphide bond A transmembrane region Amino acid binding site Antigen binding site Cytoplasmic tails
What does each polypeptide chain in a T cell receptor have?
A variabel region
A constant region
What does the transmembrane region do in a T cell receptor?
Polypeptides are inserted into this region so that they are inserted in to the plasma membrane pf the T cell so that they are expressed on the outside of the T cell
Where is the amino acid binding site found on the T cell receptor?
At the amino terminus end of each polypeptide chain
What makes up the antigen binding site?
Both the polypeptide chains