Flashcards in Innate immunity Deck (40):
What is the primary set of cells that differentiates the innate immune system from the adaptive immune system?
Two types of phagocytes
Macrophages and neutrophils
Describe four key features macrophages
-Reside in normal cells
-Often the first cells to encounter a pathogen
-Increase in number during infection
Four key features of neutrophils
-Most abundant type of white blood cell in circulation
-Rarely found in normal tissues
-Can be quickly recruited to the site of an infection
Where are tissue-bound phagocytes found?
Located everywhere, but are concentrated in the lung, skin, liver, and spleen
Coating of some particles by molecules that enhance recognition by phagocytes
What are the mechanisms of opsonization by the innate immune system vs adaptive immune system?
The adaptive immune system coats the particles with proteins from the complement system, and adaptive immune system uses antibodies
When activated, immune system cells (mostly macrophages) release cytokines and chemokines, as well as enzymes and peptides that kill foreign cells
Pathogen associated molecular pattern: have receptors that recognize conserved sequences in many pathogens, such as flagellin, DNA/RNA sequences, etc.
Names of PPRs
Toll-like receptors, NOD-like receptors, RIG-I helicase-like receptors, and C-type lectin receptors
Definition of inflammation
General term for accumulation of fluid, plasma proteins, and white blood cells in tissues subject to injury
What is the intention of inflammation?
To wall off the offending agent
To what is inflammation linked?
First step in inflammation process
Vasodilation for the movement of additional mediators and white blood cells to the area of injury
Second step in inflammation process
Increased vascular permeability
Third step in the inflammation process
Movement of leukocytes into sites of infection
What are the main cell types in the site of inflammation through time?
Neutrophil is first, then macrophages, and T cells come later
How long does it take for the innate system to be activated?
Can be activated in minutes
Which PRRs are transmembrane and which are soluble?
TCRs and CCRs are transmembrane; NCRs and RCRs are soluble
On what types of cells are PRRs most likely found?
Macrophages, dendritic cells, and monocytes
How do PRRs differentiate DNA between self and non-self?
By the location of the DNA; for example, DNA would be in the nucleus. If there isn't one, like in bacteria, then it would know it was a non-self cell
How does the PRR know what to recruit?
By whatever PAMP is activated; for example, if viral DNA is recognized, the subsequent cytokine release will be for that of cells specialized in killing/sequestering viruses
Final common path of pro-inflammatory response
Release of NF-kappa-B
One of the most important factors in the inflammatory response
Activation of IL-1 beta requires activation of what?
What does the inflamemasome do?
Activates a protease called caspase I, which cleaves IL-1 beta to the mature form
Most important secreted PRR
Mannose binding lectin (MBL), which activates complement cascade
How does the complement system bridge the gap between
-Augmenting antibody response and immunological memory
-Lysing foreign cells
-Clearing apoptotic cells and immune complexes
Three pathways to activate the complement system
Classical pathway, lectin pathway, and alternative pathway
Antigen dependent: occurs when C1 interacts with IgM or IgM complexes
Antigen independent: Polyanions (heparin, protamine), gram-negative bacteria, or CRPs react directly with C1
Mannose binding lectin binds to N-acetylglutamine, fructose, or mannose on bacterial cells, yeast cells, or viruses
Components of a pathogen's cell wall cleave C3
Final uniting step between the three pathways of complement activation
Cleavage of C3 into C3a and C3b by C3 convertase
What does C3b do?
Helps phagosomes bind the pathogen and engulf it
They are lymphocytes, but express no or very little diversity in their receptors
How many types of ILCs are there?
Type one ILCs
NK and NKT cells; produce pro-inflammatory cytokines, releases IFN-gamma, and activates DCs
Type II ILCs
Release IL-4 and help maturation of DCs
Type III ILCs
Releases IL-17, which helps recruit