Week 6 - Phagocytes

Front 1

Describe the half life of neutrophils and eosinophils. What do they contain to fight microbes? Describe the lifespan of macrophages

Back 1

Neuotrophils have a half life of 5-7 hours. They are preloaded with antimicrobial peptides,
Macrophages last about 14 days, and are long lived

Front 2

How do neutrophils fight infections? Are they associated with pus? Are neutrophils normally present in tissue, if it is not inflamed?

Back 2

They have granules to fight infection, and they are the main cell involved in pus. No, neutrophils should only be in tissues when they are inflamed

Front 3

What are the two types of granules in neutrophils?

Back 3

Specific (secretory) and azurophil (involved in phagocytosis - these contain the phagocytosed invader and kills it)

Front 4

Describe the maturation of granules in the developing WBC. Do they develop the armament they need to kill in the bone marrow in two tweeks?

Back 4

First, primary granules form, then secondary granules. They do develpo the armament they need to kill intwo weeks in the bone marrow

Front 5

How many neutrophils are made in one day? Are they short or long lived? How are they cleared?

Back 5

One billion neutrophils are made everyday. They are released from the bone marrow via cytokines. They are eaten by resident tissues macrophages in the liver and spleen

Front 6

Describe the neutrophil turnstyle.

Back 6

Neutrophils are produced in the bone marrow. They travel through the blood and extravate into the tissue. Here, they cleared by resident macrophages, which lowers the release of IL-23. In the absence of neutrophil clearance by macrophages, they release IL-23. This sends a signal back to the bone marrow, via IL-17 as intermediate, to produce and release more neutrophils

Front 7

In LAD (Cd18 deficiency), neutrophils cannot migrate into the tissues. How would this affect the neutrophil turnstyle?

Back 7

Neutrophils would not be abe to pass into the tissues, so they would not be cleared by macrophages. This would result in increased IL-23 production. Increased IL-23 production, mediated through IL-17, would cause more production and release of neutrophils

Front 8

How long do neutrophils circulate in blood - then what do the do? After they die, what is important about their spewing of their contents?

Back 8

They circulate in blood for 10 days, and enter tissues to ingest and kill microbes. The spewing of contents is a chemotactic signal to attract more cells

Front 9

What is chemotaxis? What protein typically picks up the chemotactic signal?

Back 9

Chemotaxis is the movement of cells towards or away from a stimulus. The movement is usually mediated via G protein receptors

Front 10

How are microbes recognized by the innate immune system?

Back 10

They are recognized either by antibodies attached to them, through complement proteins attached to them, or through glycans or LPS that are inherently present on microbes

Front 11

How does the process of phagocytosis work? What two ways can phagocytic cells kill?

Back 11

Phagocytic cells may ingest an invader into a phagosome. Granules then move into these vacoules, dumping their toxic contents to kill the invader. They can kill be releasing their granules or by releasing reactive oxygen products.

Front 12

What are weapons in the neutrophil arsenal?

Back 12

ROS, proteases, lyoszyme, and microbicidal peptides like defensin

Front 13

What is the oxidative burst? What enzymes are required to do it?

Back 13

The oxidative burst is the release of ROS to kill a pathogen.NADPH oxidase is required to transfer two electrons to O2 to form the superoxide anion. The superoxide anion is converted to hydrogen peroxide via superoxide dismutase. This in turn is converted into HOCl (bleach) via myeloperoxidase

Front 14

Why are proteases regulated by inhibitors?

Back 14

They can cause a lot of tissue injury, so its important to regulate them

Front 15

What are the functions of the microbicidal peptides?

Back 15

They can alter the permeability of the cell membrane, bind LPS, help phagocytosis, and put holes in the cell wall.

Front 16

What is a difference in the appearance of activated macrophages versus non activated macrophages?

Back 16

Activated macrophages have more granules relative to non activated macrophages,

Front 17

What are the two origins of macrophages? Are macrophages relatively long lived? What are some tissue specific macrophages? What are multinucleated giant cells?

Back 17

They can come from the blood as monocytes, or they can arise from cell division of tissue macrophages. Macrophages are long lived. Some tissue specific macrophages are Kuppffer cells of the liver, microglia of the brain, and alveolar macrophages of the lung. Multinucleated giant cells are the fusion of many different macrophages

Front 18

What can macrophages do besides phagocytose and kill?

Back 18

They can present antigen to lymphoctes, they can produce cytokines, and control inflammation, fibrosis and repair

Front 19

Differentiate M1 and M2

Back 19

M1 - classically activated. It is involved with phagocytosing, killing, and are considered pro-inflammatory
M2 - is involved with wound healing and are considered anti-inflammatory