Innate immunity Flashcards
Describe the innate immune system
Rapid response
Recognises a limited number of different structures
Doesn’t change upon re exposure
Describe the adaptive immune system
Takes time to develop
Highly specific for a vast number of different structures
Response improves upon re-exposure
“Immunological memory”
What do immune cells derive from?
Hematopoietic stem cell
What are the two subsets of immune cells?
Common lymphoid progenitor cell
Common myeloid progenitor cell
What are macrophages derived from?
Monocytes
Where do monocytes differentiate into macrophages?
In the blood
What is the main role of a macrophage?
To phagocytose and kill bacteria
Remove apoptotic cells
What do macrophages use to recognise non-self cells?
They use pattern recognition receptors (PRR)
To recognise pathogen associate molecular patterns (PAMPs)
How does a macrophage phagocytose a bacteria?
Kills them inside a phagolysosome
Acidification
Production of oxygen and nitrogen free radicals
Proteolytic enzymes
What does a macrophage do after it has killed a bacteria?
It prevents antigens of the bacteria
This is on the cell membrane protein MHC II
This is recognised by a T-cell
T-cell is activated
T-cell releases cytokines to promote further macrophage action
Why do macrophages produce pro inflammatory cytokines?
Attracts other immune cells to the site of infection
Causing inflammation
Name an effect of cytokines in the liver
Acute-phase proteins released
Activates the complement system
Name an effect of cytokines of bone marrow endothelium
Neutrophil mobilisation
Increases phagocytosis
Name an effect of cytokines on the hypothalamus
Increased body temperature
Increases antigen processing
Decreases viral and bacterial replication
Name an effect of cytokines on fat and muscle
Metabolisation of protein and energy stores to raise body temperature
Name an effect of cytokines on dendritic cells
Migration of dendritic cells to lymph nodes
They mature in the lymph nodes
Initiates the adaptive immune response
Name the four types of macrophage
Kupffer cell
Alveolar macrophage
Osteoclast
Microglial cell
What is a Kupffer cell?
Removes circulating bacteria and apoptotic cells in the liver sinusoids
What is an alveolar macrophage?
Removes inhaled pathogens and other particles from the lungs
What is an osteoclast?
Regulates bone density
What is a microglial cell?
Scavange dead cells, plaques and microbes in the brain
Describe a neutrophil
Most abundant leukocyte Short lifespan 1-3 days Circulates in the blood Recruited to sites of infection Phagocytose and kill bacteria
How do neutrophils enter tissues?
Neutrophils circulate in the blood
Macrophages release cytokines when they notice an infection
Cytokines are displayed by the endothelium
Cytokines activate the endothelium
Neutrophils enter tissue
Name the four stages to a neutrophil crossing the endothelium
Rolling adhesion
Tight binding
Diapedesis
Migration
How do neutrophils destroy bacteria?
Phagocytosis
Phagosome binds with primary and secondary granules
Rac2 induces NADPH oxidase producing O2-
Acidification releases granule proteases
Which cells deal with pathogens that are too large to be phagocytosed?
Mast cells
Basophils
Eosinophils
What is a natural killer cell?
Derived from same precursor as lymphocytes
They recognise virally infected cells
Describe the action of a natural killer cell
Recognises patterns specific to viral infection
Releases granules that kill the virally infected cell
Cell is then digested by macrophages
What do dendritic cells do?
Take up microbial material
Migrate to lymph nodes to activate T cells
What activates the cells of the innate immune system?
C3
What do virally infected cells express?
Type 1 IFN
