1E - Cells of the Immune System

Question 1

cells of the mononuclear phagocyte system

Answer 1

• Originate in the bone marrow
• Derived from monocytes
• Play an important role in both in the innate and adaptive immune response in inflammation, tissue removing and repair

Question 2

tissue macrophages and related cells are derived from

Answer 2

monocytes

Question 3

macrophages initiate the immune response by

Answer 3

• Macrophages and related cells in the skin, lungs and liver conduct surveillance and if they detect pathogens or other sources of antigen, they will initiate the immune response
• Macrophages initiate the immune response by releasing chemicals (chemokines) that attract other inflammatory cells to the site (chemotaxis)

Question 4

chemokines

Answer 4

chemicals released to invoke an immune response

regulate cells involved in the immune response

Question 5

chemotaxis

Answer 5

attraction of inflammatory cells to the site of inflammatory response

Question 6

function of macrophages

Answer 6

engulf damaged cells, bacteria, virus, infected cells and other foreign material

Question 7

phagocytosis

Answer 7

engulfing damaged cells, bacteria, virus, infected cells and other foreign material

Question 8

phagocytosis in the macrophage

Answer 8

• The engulfed material in a phagosome joins with a lysosome to become a phagolysosome
• Inside the phagolysosome that material is degraded into smaller pieces = antigen processing
• They present the smaller pieces (antigens) to cells of the adaptive immune system (usually a T-cell) = antigen presentation

Question 9

antigen processing

Answer 9

Inside the phagolysosome that material is degraded into smaller pieces

Question 10

antigen presentation

Answer 10

They present the smaller pieces (antigens) to cells of the adaptive immune system (usually a T-cell)

Question 11

osteoclasts

Answer 11

part of the mononuclear phagocyte system and help remodel bone

Question 12

giant cell formation

Answer 12

• Macrophages often form giant cells
◦ (With bones) to remodel bone
◦ Giant cell formation also occurs in some cases of disease (tuberculosis)

Question 13

dendtritic cell

Answer 13

conduct surveillance in tissues that contact the environment
• Originate in the bone marrow
• Important in antigen presenting cells
• Dendritic cells are the most important cell for initiating the primary immune response to protein antigen

Question 14

locations of the dendritic cell

Answer 14

◦ Found in the 
	‣ Nose 
	‣ Lungs 
	‣ Stomach 
	‣ Intestines 
	‣ Skin (lagerhands cells)

Question 15

migration of the dendritic cell

Answer 15

to the regional lymph nodes and present the antigen to the cells of the adaptive immune system (T and B lymphocytes)

Question 16

neutrophils

Answer 16

the first cells to arrive at the site of injury = first responders
• Important in the innate response but work even better if activated by the adaptive immune response
◦ Phagocytic
◦ Short lived in tissue
◦ Arrive in large numbers → purulent discharge
◦ Commonly associated with bacterial infections
Neutrophils are “granular” leucocytes

Question 17

polymorphonuclear grandular cells

Answer 17

(Poly=many, morpho=shape) (H&E stain) (H→ purple) (E→ pink)

Question 18

granules of the neutrophil

Answer 18

• The granules of the neutrophil are field with enzymes, antimicrobial peptides and proteins
• The granules in neutrophils do not stain (neutral)

Question 19

hematoxylin

Answer 19

stains nucleic acid (basophilic - purple)

Question 20

eosin

Answer 20

stains cell proteins (acidophilic - pink)

Question 21

extravasation

Answer 21

move out of the blood and into the tissues

Question 22

neutrophils elimination of foreign material

Answer 22

Neutrophils kill microbes and tumor cells and eliminate foreign material by phagocytosis
• Foreign material is digested in phagolysosome
• Neutrophils release the contents of their granules into the tissues surrounding the injury
◦ Sometimes this can cause damage to healthy tissue too

Question 23

Eosinophils

Answer 23

polymorphonuclear granular leucocytes
• Eosinophils increase in the blood in parasitic and allergic disease
• Attracted to the site of inflammation by histamine
• Release of inflammatory granules can cause extensive tissue damage (eosinophilic granulomas in horses)

Question 24

histamine

Answer 24

?

Question 25

Eosinophils stain

Answer 25

• The granules in eosinophils take up the eosin when stained with hematoxylin and eosin (H&E) = hot pink

Question 26

basophils

Answer 26

polymorphonuclear granular leucocytes • These cells are very important in allegoric reactions • Granule in basophils take up the hematoxylin and stain dark purple ◦ The granules obscure the nucleus • Rarely seen in blood films

Question 27

mast cells

Answer 27

normally reside in the tissues and are not normally found in the blood • Release histamine and other (preformed) key mediators of inflammation • Larger than basophils • Mast cells have metachromatic granules that stain bright blue with a special stain called toluidine blue

Question 28

chemical mediators

Answer 28

Many chemical mediators activate mast cells and many chemicals are produced by mast cells to activate more cells

Question 29

Natural killer cells

Answer 29

Natural Killer (NK) cells are mononuclear but have granules smaller than monocytes but are larger than lymphocytes • Important in the innate immune response • Have non-specific response • Important in early response to tumor cells and viral infections, and other intracellular pathogens • Does not require specific antigen

Question 30

difference between T lymphocytes and NK cells

Answer 30

Unlike cytotoxic T lymphocytes, NK cells attack cells that do not express MHC • Virus infected cells and neoplastic cells may not express MHC and this makes them susceptible to NK attack ◦ MHC like a cell name tag, helps the immune cell to identify if the cell is self vs nonself