Innate Immunity 2 Flashcards
What must innate immunity recognise?
Highly conserved and essential components of microbes to counter the rapid evolution of microbes
Name 4 key families of Pattern Recognition Receptors
- Toll-like
- Rigl-like
- NOD-like
- C-type lectin
What does PAMPs stand for?
Pathogen-associated molecular patterns
What 2 TLRs form dimers?
- TLR1 with TLR2
- TLR6 with TLR2
What does TLR1 coupled with TLR2 recognise?
Diacyl lipopeptide
What does TLR6 coupled with TLR2 recognise?
Triacyl lipopeptide
What does TLR3 recognise?
dsRNA
What does TLR4 recognise?
LPS
What does TLR5 recognise?
Flagellin
What does TLR7 recognise?
Imidazoquinoline
What does TLR9 recognise?
CpG DNA
How does the immune system recognise PAMPs?
Pattern-recognition receptors (PRRs)
Where are TLRs which recognize nucleic acids found?
Localized inside cells as they promote discrimination between viral and self nucleic acids
What occurs if a TLR is engaged?
It produced signals, activating transcription factors which causes gene transcription in the nucleus to produce chemokines and interferons
What is the main pathway activated following TLR engagement?
NF-kB pathway
What 5 things are under the control of NF-kB oathway?
- Inflammatory cytokines
- Adhesion molecules
- Immune effector molecules
- Chemokines
- Pro-survival molecules
What is the main chemokine which attracts neutrophils?
IL-8
What is the function of ICAM-1 adhesion molecules?
Promote adhesion of neutrophils on vascular endothelium to allow the neutrophil to move inside tissues
What is the function of FasL immune effector molecules?
Control apoptosis
What is apoptosis?
Death of immune cells
What is the function of pro-survival molecules?
Allows immune cells to survive longer during infection
Name 5 cytokines produced by macrophages in response to bacterial challenges
- IL-1
- TNF-a
- IL-6
- IL-8
- IL-12
What are the 4 local effects of IL-1?
- Activates vascular endothelium
- Activates lymphocytes
- Local tissue destruction
- Increase access of effector cells
What is the local effect of IL-6?
Lymphocyte activation increases antibody production
What is the local effect of IL-8?
Chemotactic factor recruits neutrophils, basophils and T cells to site of infection
What are the 2 local effects of IL-12?
- Activates NK cells
2. Induced differentiation of CD4 T cells into Th1 cells
What are the 3 local effects of TNF-a?
- Increase vascular permeability
- Increased entry of IgG complement and cells to tissues
- Increased drainage to lymph nodes
What are the 2 systemic effects of IL-1?
- Fever
2. Production of IL-6
What are the 3 systemic effects of TNF-a?
- Fever
- Shock
- Mobilization of metabolites
What are the 2 systemic effects of IL-6?
- Fever
2. Induces acute-phase protein production
What does TNF-a stand for?
Tumour Necrosis Factor Alpha
Give 5 characteristics of TNF-a
- Derived from macrophages and T cells
- Induces neutrophil activation
- Activates endothelial cells
- Long-term it can induce cachexia
- Acts on the hypothalamus to induce fever
What occurs once complement pathways are activated?
- Compliment proteins are created
- These bind to mast cells which release histamine
- This diffuses to endothelium which augments vascular permeability, facilitating migration of immune cells
What 3 substances are produced due to tissue damage?
- Bradykinin
- Fibrin
- Fibrinopeptides
What 4 things does bradykinin, fibrin and fibrinopeptides produce?
- Swelling
- Pain
- Heat
- Redness
What are 2 roles of antiviral immunity?
- Blocking infection
2. Blocking viral replication
Name 3 antiviral effects of IFN-a and IFN-b
- Induce resistance to viral replication
- Increase MHC class 1 expression
- Activate NK cells
What produces IFN?
Virus-infected cells
What is the function of MHC class 1 proteins?
Augment cytotoxic T cell action
What can be a potential problem with MHC class 1 expression?
Some viral cells can inhibit MHC class 1 expression
How does the body circumnavigate the virus-infected cells inhibiting MHC class 1 expression?
- NK cells have inhibitory receptors of MHC class 1 proteins
- If MHC class 1 protein expression is inhibited, NK cells target the virus-infected cell
- NK cells release lytic granules outside to target virus-infected cell
