IAI - innate immune protection Flashcards
what is innate immunity?
Innate immunity is a non specific defence mechanism that a host uses immediately or within several hours after exposure to antigen.
describe what happens in 0- 96 hours in innate immunity
0-4 hours = innate immunity (natural immunity)
4-96 hours = Early, induced response
> 96 hours = Acquired immunity (adaptive immunity)
what are the physical/anatomical barriers of the innate immune system?
- skin
- GI tract
- respiratory tract
- mucosal epithelia
what are the secreted compounds of the innate immune system?
- antibacterial compounds
- complement
- natural antibodies
- cytokines
What are the cellular components of the innate immune system?
- phagocytes
- NK cells
what antibacterial compound does the skin produce against e-coli?
psoriasin
How does the respiratory tract prevent entry of pathogens?
- difficult to penetrate due to compact structure and tight cell junctions
- cilia move continuously to move pathogens so they are unable to settle
- mucus traps bacteria to be coughed out or moved with cilia
what is the name for the disease when the cilia cant move?
Primary ciliary dyskinesia
Describe 2 ways that the GI tract provides physical barrier protection?
-
peristalsis movement
wave-like contractions of GI tract to keep bacteria moving -
HCL production + low pH
acidic conditions, activation of acid hydrolyses to destroy bacteria
Describe mechanical and secreted protection in the eyes.
- Blinking occurs first - mechanical
- Then tears - secretion
- Tears, sweat and saliva contain lysozyme which destroys bacteria walls.
What 3 barriers prevent pathogen entry?
- Physical
- Mechanical
- Secreted
How does the innate immune response recognise antigens?
via PAMP:
PAMP = Pathogen Associated Molecular Patterns
What are the two important characteristics for a molecules to be designated a PAMP?
- The PAMP should be present in the microorganism but not the host (so you can differentiate between self and non-self)
- The PAMP must also be essential for the survival of the pathogen
What PAMP is found in gram negative bacteria?
Lipopolysaccharide (LPS) is found in the wall of all gram-negative bacteria.
What PAMP is found in gram positive bacteria?
Lipoteichoic acid is found in the cell wall of all gram-positive bacteria.
How does the host recognise these PAMPs?
Pattern Recognition Receptors (PRR).
what is LPS made from?
- A lipid A molecule
- and the O polysaccharide.
what does the O polysaccharide in LPS tell you?
The O polysaccharide in LPS is the part that tells you what type of gram negative bacteria it is
What are the 3 types of PRRs?
Collectins - soluble receptors that float around in the serum
Toll like receptors (TLRs) - these are membrane bound receptors not only on the cell surface but also on membranes within cells.
Nod like receptors - these sit in the cytoplasm of cells
Describe collectins.
- serum, soluble
- family of proteins present in solution
- Collagen like region and lectin region
- collagen: interacts with effector part of immune system (signal)
- lectin: binds to sugar molecules on surface of pathogen (mannose)