Innate Immunity Flashcards
What is innate immunity?
The defence system that one is born with
What does innate immunity depend on?
Physical and chemical barriers
What is the function the physical and chemical barriers?
First line of defense in the immune response
What is a self-marker?
They are recognised by the immune system of an organism as being part of that organism.
What causes the self marker to be recognised?
The presence of marker molecules known as HMC
What is non-self?
Agents that are not recognised by the immune system as being part of the organism.
What identifies non-self?
The presence of receptors that identify the agent as an antigen.
What does innate immunity look for?
PAMPs and DAMPs
What are PAMPs?
Pathogen associated molecular patterns
What are DAMPs?
Danger associated molecular patterns
Where are PAMPs derived from?
Microorganisms and thus drive inflammation is response to infections.
What is a well known PAMP?
Lipopolysaccharide, cell wall of gram-negative bacteria
Where are DAMPs derived from?
Host cells, such as tumour cells, dead or dying cells, products released from cells in response to signals
What do DAMPs induce?
Sterile inflammatory response
Where are DAMPs created or exposed to?
Environments of trauma, schema or tissue damage
Which molecular patterns do not require a pathogenic infection?
DAMPs
Examples of environments where DAMPs appear?
MI, cancer, autoimmune disease, atherosclerosis
How are PAMPs and DAMPs recognised?
Immune cells have pattern recognition receptors
What follows after the binding of the PRRs to PAMPs/DAMPs?
Recruitment of phagocytes, natural killer cells and leukocytes
What are the three lines of defence?
Physical and chemical barrier,
Innate Immune Response
Adaptive Immune Response
What are some examples of physical first lines of defence?
Skin,
Nasal hair,
Eyelashes & Eyelids
Mucous Membranes
Mucociliary Clearance
Urination
What are some examples of chemical first lines of defence?
Low pH (skin, gastric acid, vagina)
Antimicrobial molecules (IgA, Sebum, Mucous)
What are some examples of biological first lines of defence?
Microbiome
What is the process of innate immunity?
Phagocytes bind to pathogen
Wrap around their cell membrane around pathogen
Engulf pathogen and destroy them
Pathogens are broken into small pieces and displayed to phagocytes
Recognised cytosine T-cells, destroy the phagocytes with pathogen inside
During phagocytosis what do the receptors bind?
Bind ligand molecules on the target such as pathogens or dead cells.
What happens as receptors bind more and more ligand molecules?
Cell membrane progressively engulfs the target
What happens upon full engulfment?
Phagosome is formed, fuses with lysosomes leading to digestion of target.
What is the process of the complement system?
Complete protein activated –> Recruit WBC to the site of infection which triggers inflammatory response.
Which are the non-specific defence mechanisms?
First and second lines of defence
What is the specific defence mechanism?
Third line of defence
When is third line of defence activated?
When other first and second lines of defence have been exhausted
What are the main phagocytes?
Macrophages
What are the macrophages in the lungs called?
Alveolar macrophage
What are the macrophages in the liver called?
Kupffer cells
What are the macrophages in the connective tissue called?
Histocytes
Why do macrophages release cytokines?
To bring in reinforcement: neutrophils
What are neutrophils?
Granulocytes that contain histamine
What does histamine cause?
Vasodilation and thus triggers inflammation