Macrophages 1 Flashcards
A macrophage is an innate immune cell present in tissue. What is it called when in blood?
Monocyte
Is a monocyte in the blood an active cell?
No. Compare this to a neutrophil in the blood which is active.
What is the maximum time that a monocyte will be in a blood vessel before it migrates into the tissue?
10 to 20 hours. It will get out sooner if there are chemotactic factors in the tissue.
How far can a macrophage travel from the blood vessel into tissue?
100 micrometers
What is the maximum distance any tissue in the body is from a blood vessel?
50 micrometers
What 2 things happen after a monocyte enters the tissue for it to become a mature macrophage?
- It increases size by 5x
- It’s lysosomes mature
What are macrophages called when they are in the blood?
Monocytes
What are macrophages called when they are in the tissue and attached to cells?
Histiocytes
What are macrophages called when they are under the skin?
Langerhans cells
How many bacterial cells can a liver macrophage (in the sinuses) phagocytose in 1 seconds?
100
* After this the blood that ends up in the general circulation is generally pathogen free
What are the resident macrophages of the liver called?
Kupffer cells
What effect does chronic EtOH ingestion have on the enteric portal system (cells)?
It causes the GI barrier to be more permeable which allows more pathogens into the portal system
When macrophages (kupffer cells) in the liver are stimulated by excess bacteria (via increased permeability from chronic EtOH) what do they release?
Transforming Growth Factor beta (TGF beta)
What does TGF beta in the liver do (released by Kupffer cells)?
They act on stellate cells (in the liver sinusoids) which release amyloid. This is an attempt at repair (which is unnecessary
This leads to collage deposition and this leads to liver cirrhosis
What function do macrophages in the endothelium of the spleen performs?
They capture old RBCs
What are alveolar macrophages called?
Dust cells
What do pulmonary macrophages (dust cells) in the alveoli do when they can’t kill a pathogen like mycobacterium TB?
They all fuse together and form a giant cell (aka epithelioid cell)
Has horseshoe nucleus
The brain is immune privileged. What does this mean?
It means that normal immune cells and chemicals cannot enter the brain
The brain is immune privileged. What does this mean?
It means that normal immune cells and chemicals cannot enter the brain
What are the macrophages of the brain called?
Microglia
What are the macrophages of the bone called?
Osteoclasts
What are the 3 primary functions a the macrophage?
Phagocytosis
Antigen presentation
Cytokine secretion
What does the TLR-4 along with CD14 on macrophages recognize?
Gram negative bacteria
What does the TLR-2 along with CD14 on macrophages recognize?
Gram positive bacteria and yeasts
What are PAMPs?
Pathogen Associated Molecular Patters that TLRs recognize
How many times can a macrophage phagocytose compared to a neutrophil before it dies?
Macrophage = 100
Neutrophil = 20
What can phagocytose the largest particles, macrophage or neutrophil
Macrophage
