Innate immune protection Flashcards
What is an innate immune response?
The first part of the immune response before an adaptive response.
How does the innate immune system detect non-self cells?
Using a few receptors that are highly conserved structures present in pathogenic organisms
What are PAMPs
Pathogen associated molecular pattern; present in the microorganism but not in the host. Is an essential structure for the survival of the pathogen.
What is present in all Gram negative bacteria?
LPS, Lipopolysaccaride.
Has a lipid A (common to all Gram-negative bacteria) and an O-polysaccharide (varies between organisms)
What is present in all Gram positive bacteria?
Lipoteichoic acid
What is a PRR in the innate immune system?
Pattern recognition receptor- recognises PAMPs then sends a signal to the nucleus to cause upregulation of molecules involved in the innate immune system.
How do collectins work in the innate immune system?
Family of proteins
Made up of a collagen-like part and 2 lectin parts. It detects mannoses and fucoses on the surface of the bacteria. While the sugars are not themselves unique to the bacteria, the pattern/spacing is. This allows for differentiation between self/nonself cells.
How to do toll like receptors (TLRs) work in the innate immune system?
There are loads of them and they all are receptors for a particular characteristic of a pathogen.
How do NOD like receptors work in the innate immune system?
They recognise the components of both Gram positive and negative bacteria.
How is complement in the innate immune system?
Series of proteins produces by the liver - circulates in blood + tissue fluids. Operates via a cascade, one product induces the formation of the next. Key protein involved is C3 which is cleaved by C3 convertase. (!)
What are they 3 pathways by which a complement cascade can occur?
Classical, MB-lectin, Alternative
What forms the membrane attack complex in the innate immune system?
Terminal components of the complement cascade: C5b, 6,7,8,9. Punches a hole in the membrane of the cell causing cell lysis.
Not all microorganisms are killed in phagocytosis; what are some alternative methods used by the innate immune system to kill?
Respiratory burst:
NADPH oxidase complex forms hydroxyl radicals + hypochlorite ions (oxygen radicals) causing DNA damage + alterations in bacterial membrane
Production of reactive nitrogen intermediates:
L-arg -> L-citralline generates NO radicals
Catalysed by enzyme inducible NO synthase (iNOS, NOS2) induced by cytokines + bacterial components.
What is respiratory burst in the innate immune system?
Respiratory burst:
NADPH oxidase complex forms hydroxyl radicals + hypochlorite ions (oxygen radicals) causing DNA damage + alterations in bacterial membrane
