Recognising Pathogens. Flashcards
What do antibodies allow for?
Components of the immune system to recognise pathogens.
What is responsible for releasing antibodies?
B lymphocytes.
What happens once antibodies are released?
They bind to the invading cell/virus and mark it for destruction by a phagocyte.
What are the 2 main regions on an antibody?
The FAB region.
The FC region.
What does the FAB region of an antibody bind to?
It is highly specific and only binds to a single type of pathogen.
What part of a pathogen will the FAB region of a pathogen bind to?
To antigens on the pathogen.
Is the FAB region of an antibody capable of changing?
Yes, it changes so it can bind to different pathogens.
What is the function of the FC region of an antibody?
It binds to phagocytes.
Does the FC region of an antibody ever change?
No.
How does the binding of an antibody to an antigen affect its relationships with other immune cells?
Complement proteins and other immune cells have a higher affinity to the antibody when it is bound to an antigen.
What happens to the antibody when the FAB region binds to the antibody?
There is a conformational change at the FC region making it easier for immune cells to bind to it.
Why will immune cells not bind to antibodies unnecessarily?
As there is no conformational change.
How do neutrophils and macrophages recognise pathogens?
Via their PRR receptors.
Will all PRRs be able to recognise all pathogens?
No, some may only recognise one class of pathogen e.g. all gram negative pathogens.
What part of a pathogen is recognised by a PRR?
A PAMP.
What is the most important group of PRRs?
Toll like receptors (TLRs).
What is recognised by toll like receptors?
Conserved molecular patterns on viruses and bacteria.
Can TLRs recognise intracellular or extracellular pathogens?
Both.
TLRs are expressed in what 6 types of cells?
Mast cells.
Dendritic cells.
Macrophages.
Neutrophils.
Eosinophils.
Some epithelial cells.
What 2 things does the interaction between a TLR and a PAMP allow for?
For immune cells to recognise pathogens.
The production of cytokines which promote the inflammatory response.
Are natural killer cells part of the innate or adaptive immune system?
The innate immune system.
What will be killed by natural killer cells?
Infected cells.
Tumour cells.
What is the only lymphocyte that functions within the innate immune system?
Natural killer cells.
What is the innate immune systems line of defence against intracellular pathogens?
Natural killer cells.
What 2 types of cells are capable of killing infected host cells?
Cytotoxic T cells.
Natural killer cells.
How do cytotoxic T cells recognise infected host cells and tumour cells?
Via antibodies.
Do natural killer cells use antibodies to recognise infected host cells?
No.
Do natural killer cells kill microbes?
No, they only kill host cells.
Can NK cells recognise complement proteins?
Yes, if these proteins are attached to a host cell then the natural killer cell will kill the cell.
What will an NK cell do to a host cell that is expressing interferons?
The interferons tell NK cells that something is wrong within the cell.
This causes the natural killer cell to get rid of it.
What is a major interferon that is produced by damaged cells?
Interferon alpha.
What is expressed on the cell surface on all nucleated cells?
A molecule called MHC-1.
What is the function of an MHC-1 molecule?
It tells immune cells not to kill them.
What happens to the MHC-1 molecule on a virally infected cell?
They will not express MHC-1.
Cells that do not express MHC-1 will be killed by a macrophage.
