Innate Immunity - Cytokines Flashcards
Small proteins secreted by activated nucleated cells.
Cytokines
Proteins used to communicate with other cells
cytokines
Proteins that activate or suppress (i.e. modulate) most cellular behaviour.
Cytokines
True or False? Cytokines only have a role in innate immunity.
False. They have a role in both innate and adaptive immunity.
Describe the mode of action of a cytokine.
Cytokine binds to its receptor expressed on the cell surface which, through signalling, induces the cell how to behave
Which cytokines have a key role in innate immunity?
Chemokines
Interferons
pro-inflammatory cytokines
Which cytokines have a key role in hematopeoisis?
CSFs
GFs
What are some examples of pro-inflammatory cytokines?
ILs
TNFs
_________ (i.e. becoming myeloid or lymphoid progenitors) is dictated by _________.
hematopoeisis
cytokines
An activated cell secretes ______ types of cytokines ________.
many
simultaneously
A phagocyte binding a pathogen results in what?
- Phagocytosis
- Release of cytokines
a) pro-inflammatory cytokines
b) chemokines
Describe the pathway (or draw) from phagocyte-pathogen interaction to release of cytokines.
- Phagocyte binds to pathogen through PRR-PAMP interaction
- Phagocyte gets activated
- Initiates phagocytosis and release of cytokines
- Pro-inflammatory cytokines and chemokines are released
What do pro-inflammatory cytokines do?
Activate endothelial cells
vasodilation and increase permeability
How do activated endothelial cells contribute to the inflammation reaction?
Activated endothelial cells:
1. Vasodilate
2. Increase blood vessel permeability
(This allows circulating immune cells and proteins to enter the infected tissue)
Which immune cells are initially located in the blood?
(immature) dendritic cells, neutrophils, monocytes, NK cells (T-cells)
What happens to monocytes when they enter infected tissues?
Mature into macrophages
What do chemokines do?
These are chemo-attractant molecules which attract immune cells.
Why can WBCs only penetrate veins, rather than arteries?
Main reason: lower blood pressure (cells cannot adhere to endothelial cells)
other reason: thinner walls
Describe the process of inflammation when an extracellular pathogen breaches the tissues.
- Extracellular pathogen breaches the tissue
- Tissue-resident phagocytes (immature dendritic cells and macrophages) bind to pathogens through PRR-PAMP interactions - get activated
- Activated phagocytes initiate phagocytosis and release cytokines (Chemokines and pro-inflammatory cytokines)
- Pro-inflammatory cytokines activate endothelial cells
- Activated endothelial cells vasodilate and increase vascular permeability
- Circulating immune cells (neutrophils, immature dendritic cells, monocytes, NK cells (T-cells)) are attracted to site of injury, and enter the infected tissue
During inflammation, what causes redness?
Swelling?
Redness is caused by vasodilation
Swelling is caused by increased vessel permeability and the outflow of fluid into the tissues
How is fever initiated?
PRR-PAMO –> pro-inflammatory cytokines –> inflammation –> cytokines return to blood –> induce hypothalamus to release prostaglandins –> induce fever
Why is fever a good thing in innate immunity?
Fever kills pathogens - as most pathogens require a lower body temperature to replicate Fever causes sweat: - flushes out microbes - contains antimicrobial peptides - contains IgA antibodies
For what type of pathogen are IFNs important?
Viruses (obligate intracellular parasites)
What are the two functions of IFNs?
- IFNs tell NK cells to kill the virus-infected cell
2. IFN induces nearby healthy cells to produce antiviral enzymes to protect themselves (inhibit viral replication)
