review of innate immunity Flashcards
what has an innate immune response?
everything
why do we need an innate immune response?
adaptive immune response ( antibodies and T cells) is too slow to protect us from new pathogens
how long does it take for an antibody response to kick in?
around 5 days
why do we need an innate response?
provides first line defence to keep infection under control until adaptive immunity kicks in- AB + T cells otherwise response would be too slow. ensures survival of individual until other response
what response is required to resolve an infection
both innate and adaptive
what are they key differences between adaptive and innate immunity
adaptive- involves very specific recognition of infectious agents, ie antigen
innate has no specific antigen recognition
innate immunity involves recognition of broadly conserved features of different classes of pathogens (PAMPS)
what does PAMP stand for
Pathogen-associated molecular pattern molecules (PAMPs)
what is a PAMP
- molecules present only on pathogens and not on host cells, they’re essential for the survival of pathogens.
9PAMPs) are derived from microorganisms and recognized by pattern recognition receptor (PRR)-bearing cells of the innate immune system as well as many epithelial cells.
invariant structures shared by entire class of pathogens, things pathogens cannot avoid having for their life cycle. these are enough to alert your immune system
State examples of PAMPs for G -ve, G+ve, bacteria, and viruses?
- Gram-negative bacteria; lipopolysaccharides (LPSs) found in outer membrane- endotoxin
- Gram-positive bacteria; teichoic acid, lipoteichoic acid, peptidoglycan found in outer membrane
- Bacterial flagellin
- Abnormal protein glycosylation
- Abnormal nucleic acids - viruses
for every pamp, there has to be a receptor, what is this receptor called?
pattern recognition receptor- PRR
what is a PRR
host factor that specifically recognise a particular type of PAMP. they are invariant
what is special about PRR genes?
they are germ line encoded.. meaning these genes dont rearrange, theyre the same in every cell
-These receptors evolved to recognize conserved products of microbial metabolism produced by microbial pathogens,
briefly, what are the three classes of functional PRRs?
extracellular, intracellular, secreted
what is an extracellular PRR?
recognise PAMP outside the cell and trigger a coordinated response to the pathogen
what is the intracellular PRR?
- cytoplsmic
- recognise PAMP inside cell and act to coordinate response to pathogen
what is secreted PRR?
they go off into the bloodstream and act to tag circulating pathogens for elimination ie compliment system
what are the 5 components to the innate immune system?
they all trigger each other
- The inflammatory response
- Phagocytes
Monocytes/granulocytes/neutrophils - Complement
- Cytokines, chemokines and anti-microbial
peptides (AMPs) - Natural Killer cells
what is the inflammatory response?
A generic defence mechanism whose purpose is to localize and eliminate injurious agents and to remove damaged tissue components
effect of infalmmatory response?
- Enhanced permeability and extravasation
- Permeability, so cells can get to site of infection
- Extravasation = cells from blood to tissue
- Neutrophil recruitment
- Enhanced cell adhesion
- Enhance clotting
what is the infalmmatory response triggered by?
by the release of pro-inflammatory cytokines and chemokines at the site of infection
what is a chemokine
chemo attractants, signals at high conc where pathogen is and therefore low concs eveyrhwere else and that conc grad is what stimulates neutrophils etc to go to source
what are the three different types of phagocytes
- monocytes
-granulocytes
-neutrophils
what are the three different types of phagocytes
- monocytes
-granulocytes
-neutrophils
what are the three types of phagocytes that can carry out phagocytosis?
Dendritic cells, macrophages and neutrophils
- Considered as professional phagocytes
state the 3 distinct roles of macrophages and dendritic cells in immunity
- phagocytosis, the material is destroyed in lysosomes
2.triggering inflammatory response
3.Peptides from broken down pathogens can be presented through MHC and promote the development or recall of an adaptive T cell response (more for D cell)
what is MHC
The major histocompatibility complex (MHC) isa series of genes that code for cell surface proteins that control the adaptive immune response.
what are 5 ways in which phagocytes recognise pathogens
- By detecting phosphatidylserine on exterior membrane
surface -cells undergoing apoptosis - By detecting “atypical sugars” (e.g. mannose, fucose, beta-glucan) on cell surfaces
- By Scavenger receptors → receptors that are non-self
- By “passive sampling’
- By detecting complement proteins bound to the pathogen surface
what is a scavenger receptor
receptor that recognise non self
what is a scavenger receptor
receptor that recognise non selft
two broad ways in which phagocytes recognise and eat pathogens
-cell mediated
-passive sampling
the main aim of the complement system?
- number of soluble proteins made and secreted by the liver whos job is to bind to pathogens and decorate for destruction
