Innate immunity Flashcards
What is the primary set of cells that differentiates the innate immune system from the adaptive immune system?
Phagocytes
Two types of phagocytes
Macrophages and neutrophils
Describe four key features macrophages
- Reside in normal cells
- Often the first cells to encounter a pathogen
- Long-lived
- Increase in number during infection
Four key features of neutrophils
- Short-lived
- 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
Opsonization
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
Mediator production
When activated, immune system cells (mostly macrophages) release cytokines and chemokines, as well as enzymes and peptides that kill foreign cells
PAMP recognition
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?
Tissue repair
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
IL-1 beta
