Review of Innate System Flashcards
Why do we need an innate immune response when a adaptive immune response is present?
Adaptive response is too slow to protect against new pathogens (new microbe replication fast and peaks quickly and adaptive immune system only comes after this peak) - for survival until adaptive immune response comes in
How specific is adaptive immunity?
Very specific recognition of infectious agent through protein/antigen
How specific is innate immunuty?
No specific antigen recognition
What part of pathogens are recognised by innate immunity
- recognises broadly conserved feautures on pathogens - PAMPs (pathogen associated molecular patterns)
What are PAMPs? + what is their purpose
Molecules present only on pathogens not on host cells so recognised as non self - found on all pathogens (diff types) - needed for pathogen survival
What type of bacteria are PAMPs found on?
gram positive and negative
What is the PAMP on gram negative bacteria?
lipopolysaccharides found in outer membrane
What is the PAMP on gram positive bacteria?
TETICHOIC ACID, peptidoglycan, lipoteichoic acid in outer membrane
Give examples of general PAMPs? in diff types of pathogen
Bacterial flagella
Abnormal protein glycosylation
Abnormal nucleic acids - viruses
What part of host recongises PAMPs?
PRR (pattern recognition receptor)
Why are viruses PAMPs nucleic acid?
Dont have cell wall to recongise things on surface of the pathogen
What does germ line encoded mean? + example of something that is germ line encoded
receptors that Cannot be rearranged somatically - PRRs
What are the classes of PRRs? and what does each do
Intracellular - (cytoplasmic) recognise PAMPs inside a cell - pathogen has already entered cell
Extracellular - recognise PAMPs outside cell - before pathogen enters cell
Secreted - tag circulating pathogens for elimination
How can you experiment mice reaction to see what would happen if they dont have innate response
Get rid of PRRs so no receptors to recognise PAMPs (general recongition in innate immunirt)
What are all the component of innate immunity?
Inflammatory response Phagocytes Complement Cytokines, chemokines, and anti-microbial peptides (AMPs) Natural killer cells
Name a few phagocytes?
Monocytes, NEUTROPHILS, dendritic cells
What is the purpose of an inflammatory response?
Generic defense mechanism to localise and eliminate injurious agents/damaged tissue components + prevent pathogen from leaving site of infection
What triggers inflammatory responses?
Pro-inflammatory cytokines and chemokines at the site of infeciton
What are the other effects of an inflammatory response?
Enhanced permeability and extravasation
Neutrophil recruitment
Enhanced cell adhesion
Enhance clotting
What is extravasation?
Cells can pass from blood to tissues
Why is it good to enhance cell adhesion in inflammatory response?
Neutrophils and macrophages stick to tissue at site of infection
Why is increased clotting important in inflammatory response?
Identifying restriction and restrict - cut off blood supply
Which components of innate immunity is linked to eachother?
Phagocytes, complement and cytokines, chemokines + AMPs
What is important about cell recongition in phagocytosis?
Need to know which cells are infected to produce correct cytokines and chemokines and not destroy healthy cells
What receptors are on phagocytes and what are their purposes? !!!!!!!!!!!!!
Pattern recognition receptors - Toll like receptors involved in making cytokines and chemokines NOT IN the phagocyte recognising pathogen
Diff PRR recognises what to eat and what not to
What organisms does phagocytosis happen in?
In all multicellular organisms so they all have to recongise and phagocytose debris.infected cells
What is different about neutrophils compared to the other phagocytes (macrophages and dendritic cells)?
Not involved in priming adaptive immune response , more involved in tissue repair and tissue damage (eating damage at site of infection)
recruited through cytokines produced by macrophages
What are the 3 roles of macrophages and dendritic cells ?
- Phagocytosis
- Macrophages once activated produces cytokines and chemokines to stimulate both innate and adaptive response (triggering inflammatory process)
- Pathogen peptides broken down and presented through MHC + promotes development/recall of adaptive T cell response
How do phagocytes know what to eat?
Passive sampling to detect:
- atypical sugars (mannose or beta glucan) or phosphatidlyserine (on outside of surface for apoptosing cells)
- complement proteins bound on pathogen surface
What phagocytic receptors are present on macrophages (to recongise what to eat)?
Complement receptors Mannose reeptors Lipid receptors Scavenger receptors (NOT TOLL LIKE RECEPTORS) beta glucan receptor
Why might cells be already going under apoptosis that phagocytes need to recongise?
Many viruses cause apoptosis, if phagocytes recognise these by recognising phosphatidylserine out outer surface, macrophages can ingest those cells
What do scavenger receptors recognise?
Non self particles on surface of our cells
What is passive samping?
Phagocytes constantly drinking up debris from environment
What is the complement system?
Heat sensitive component of serum that increase ability of antibodies to inactivate antigen and complement proteins act as PRR that can be activated by PAMPs (increase phagocytosis
What are the 3 pathways in the complement system?
Classical pathway
Lectin pathway
Alternative pathway
What activates the classical pathway of complement?
Antigens (PAMP) recongised by antibodies (PRR) \:ipopoylsaccharides (PAMP) recongised by lipoprotein (PRR) Abnormal phospholipids (PAMP) recongised by pentraxins (PRR)
What is the lectin pathway?
Complement system
The pamps recognised are atypical glycosylation
What is the alternative pathway?
Lack of control factors (cells have complement control factors so complement does not attack host cells, lack of means cell is seen as non self and activates alternative pathway)
Which PRR receptors involved in phagocytes knowing when cells are infected and when to produce chemokines and cytokines? (not the receptors that tell phagocytes what to eat and what not to eat)
Toll like receptors
NOD-like receptors
RIG-like receptors
111
1111
1111
What are cytokines? example
GLYCOPROTEIN HORMONES that modify behaviour of cells in immune response
most are interleukins
What are chemokines?
GLYCOPROTEIN HORMONES that act as chemotactic factors( create concentration gradient to attract specific cells types to site of infection)
What are interferons?
Main anti-viral cytokines (secreted glycoprotein hormone induced by viral infection)
What types of cytokines are interferons?
Type 1 (protect other surfaces in blood stream and tissues) and type 3 (protect epithelial cells e.g. lungs)
Why are interferons useful?
No they provide CROSS-PROTECTION (interferons produced for one infection can protect from another viral infection e.g. interferons produce from flu can protect against polio
Describe the process of interferons providing protection step by step?
Interferon made by primary infected cell that dies
Released Interferon binds to neighbouring cells triggering transcription of antiviral genes so cell doesnt allow replication when virus tries to spread - cell is now in an ANTI-VIRAL STATE (cell wont be permissive of the virus being let in or replicating)
What is the signal pathway once interferon binds to a neighbouring cell receptor?
Signal transduction e.g. JAK-STAT pathway
e.g protein kinase made causing translational arrest of viral rna and cellular rna will also not be translated but also prevents rna from virus replicating
What are AMPs? + example
Antimicrobial peptides - short peptides e.g defensins
What do AMPs do?
Disrupt cell wall leading to lysis. Offer broad protection
What are AMPs induced by?
Bacterial infection
What are NK cells?
natural killer cell - large GRANULAR lymphocytes
What do NK cells do?
Destroy (by lysing) target cells (infected and certain tumour cells) using cytotoxic molecules called GRANZYMES AND PERFORINS
What activates NK cells?
Loss of self MHC molecules on target cell surfaces AND up regulation of activation ligands (death receptors)
What ends up happening if innate immunity is defected?
Diseases associated to defect e.g. complement defect = development of autoimmune diseases such as lupus
2nd to last slide still needs flashcards
Compare speed in innate vs adaptive immunity?
Innate is fast, adaptive is slow
Compare memory in innate vs adaptive immunity?
No memory in innate, yes in adaptive
Compare receptors in innate vs adaptive immunity?
PRRs in innate
Ig and TCR in adaptive