T cell mediated immunity 2 Flashcards
What do cytotoxic t cells do after being formed by replication of an ativated cd8 t cell?
Leave the lymph nodes and are in circulation
What do cytotoxic t cells do while in circulation?
Look for cells that express the peptide they were activated against
Make nonspecific, weak interactions with cell adhesion molecules
What do cytotoxic t cells do if they recognise the peptide being presented by an MHC molecule on a cells surface?
The interaction between the target cell and the t cell is strengthened
What is an immunological synapse?
A strong interaction between a cytotoxic t cell and a cell that is presenting an antigen on MHC
What occurs as a result of immunological synapse formation?
The t cell changes its cytoskeleton so that it polarises
What occurs as a result of polarisation of the cytotoxic t cell?
Lytic granules (containing enzymes and membrane-permeabilizing proteins) fuse at the site of antigenMHC contact
What does perforin (released by cytotoxic t cells) allow to enter the target cell?
Granzymes–> serine proteases
What do the granzymes do after entering the target cell?
Start the apoptotic cascade in the target cells
What is the overall result of a cytotoxic t cell making a strong connection with a target cell?
The target cell undergoes apoptosis
What happens after the target cell has undergone apoptosis?
Macrophages come and “mop up” the cell debris
What is type 1 diabetes caused by?
Cytotoxic t cells against pancreatic beta cells that secrete insulin
What happens to the cytotoxic t cell after the target cell has undergone apoptosis?
It searches for another target cell
What do Th1 cells do after leaving the 2ndary lymphoid tissue?
Search for macrophages presenting peptides from pathogens
What does a Th1 cell do after finding a macrophage presenting a pathogenic antigen on MHCII?
Activate the macrophage
What, other than activating a macrophage, do Th1 cells do?
Secrete cytokines–>help in inflammation
What is GMCSF?
Granulocyte macrophage colony stimulating factor–> long range effect–> alerts bone marrow to produce more macrophages and neutrophils
If a B cell takes up and presents a self antigen, will the b cell be stimulated to divide by a t cell?
Probably not as it is unlikely that a t cell that will recognise self antigens
Is the antigen recognised by the antibody the same as the antigen presented on the B cells surface, and recognised by the t cell?
Not necessarily–> B cell receptor might recognise a surface antigen on the bacterium, and then a intracellular antigen might be presented on the B cell
WHat and why are Tregs used for?
Immune response suppression–> don’t want an ongoing immune response
Example of Tregs going wrong?
Tregs downregulate the activity of cytotoxic t cells against tumours–> allows the tumour to grow
What is the difference between activation of naive and memory immune cells against the same pathogen?
The reactivation of memory cells require less stringency, and so can be reactivated faster
