Lecture 7: Innate Immunity Flashcards
1
Q
what recognises antigens in innate immunity
A
- non-specific pattern recognition receptors
- germline encoded, so each receptor has its own gene
2
Q
functions of innate immunity
A
- prevents infection
- promotes acute inflammation
- responds rapidly
3
Q
what are the types of barriers to infection
A
- mechanical
- chemical
- microbiological
4
Q
examples of mechanical barriers
A
- epithelial cells joined by tight junctions in skin, gut, lungs, eyes and nose
- longitudnal flow of air or fluid in skin and gut
- movement of mucus by cilia in lungs and expelled through nose
5
Q
examples of chemical barriers
A
- fatty acids on skin
- low pH and enzymes in gut
- salivary enzymes (lysosomes) in eye and nose
- antibacterial peptides in skin, gut and lungs
6
Q
examples of microbiological barriers
A
commensal organisms (flora) that live on skin and in the gut
7
Q
how do pattern recognition receptors work
A
- detect antigens non-specifically using receptors for pathogen-associated molecular patterns (PAMPs)
- PAMPs are patterns of molecules that occur in lower organisms but not humans
- effective for distinguishing between self and non-self
8
Q
example of a pattern recognition receptor
A
- mannose binding ligand
- binds to mannose and fucose residues
- these residues are found on lower organisms and humans, but with different confirmations
- MBL only binds to confirmation of lower organisms
9
Q
what do eosinophils do
A
- believed to be important in defence against parasites
- granules contain toxic enzymes
- can perform antibody-dependent cellular cytotoxicity
- also found in sites of allergic inflammation
10
Q
types of soluble mediators
A
- cytokines
- chemokines
- complement
- interferons
11
Q
what do interferons do
A
- alpha interferon production is activated by viral infection
- work locally and on surrounding cells to stop cells dividing and synthesising new proteins, and stimulate production of antiviral proteins by the host cell
12
Q
what is the triggered enzyme cascade
A
- complements are a series of enzymes produced in the liver and circulate in bloodstream in inactive form
- when the first enzyme is activated, it activates the next and the next
- allows amplification of the immune response
13
Q
what activates the triggered enzyme pathway
A
- classical pathway set off by antigen-antibody complex
- mannose binding ligand
- alternative pathway set off directly by bacterial surfaces
14
Q
what does the complement system do
A
- produces pro-inflammatory chemical byproducts
- terminal pathway components assemble a pore which inserts into pathogen membranes
- activated complement component c3b sticks to pathogens and binds to receptors on phagocytes
