Cells of the Immune System Flashcards
What is the function of phagocytes?
- First line of defence
- Remove extracellular debris
Give 2 examples of mammalian phagocytic cells
- Macrophage
- Neutrophils
Where are macrophages usually located?
They are usually tissue resident
Where are neutrophils usually located?
The blood
What is the precursor for macrophages?
Monocytes
Give examples of important pattern recognition receptors
- Mannose receptors
- Scavenger receptors
- Toll like receptors
What chemicals do phagocytes use to kill ingested bacteria?
- Free radicals
- Acid
- Nitric Oxide
- Enzymes
What does the mannose receptor detect?
Sugars pn the surface of many bacteria and some viruses
Do macrophages have Fc receptors?
Yes
What are the differences between neutrophils and macrophages?
Neutrophils are found in the blood and macrophages in the tissues, neutrophils are much shorter lived than macrophages
What kind of pathogens are eosinophils responsible for fighting?
Large extracellular pathogens e.g. parasites
How are eosinophils activated?
By Fc receptors
Why does it not matter than activation of eosinophils take a few days?
Parasites grow more slowly than other pathogens
How do eosinophils kill parasites?
They release enzymes and toxic proteins onto the parasite
What is the role of mast cells?
Recruit additional immune cells to the site of infection
What do mast cells do in response to pathogens?
Release inflammatory mediators into the tissue
Give a similarity between mast cells and eosinophils
They are both activated in the same way
What kind of pathogens do natural killer cells deal with?
Intracellular pathogens such as bacteria and viruses, they also kill tumour cells
What kind of cells are innate anti-viral/anti-tumour cells?
Natural Killer cells
What type of cells are adaptive anti-viral cells?
Cytotoxic T cells
How do natural killer cells kill cells?
They release granules containing perforin and granzymes
How do granzymes kill cells?
They stimulate apoptosis
How are NK cells activated?
- In infected cells MHC class 1 expression is downregulated
- Cells undergo stress causing stress protein to be produced on surface
- This prompts NK cells to be switched on
What is the function of dendritic cells?
Main cell type to mediate T cell activation
How do dendritic cells mediate T cell activation?
- Activated by pattern recognition receptors at site of infection
- Travel to lymph nodes
- Activate naive T cells in LN
