Cells of the immune system

Question 1

Mucosal barrier - Epithelial cells

Answer 1

• cilia sweeps mucus

- secrete antimicrobial molecules (Eg defensins)

Question 2

Mucosal barrier - Goblet cellls

Answer 2

• secrete mucus
• traps microbes
• prevents adhesion

Question 3

Mast Cells

Answer 3

-granular appearance
-granules contain signalling substances
(Histamine, Leukotriene B4 (LTB4), Cytokines - TNFa, chemokines - CXCl2)
-alarm signal
-rapid reaction - dengranulation

Question 4

Histamine and LTB4:

Answer 4

• Blood vessels become more permeable
• more interstitial spaces
• more fluid can leave the vessel and enter surrounding tissue

Question 5

Neutrophils

Answer 5

• first responders of immune system
• trans-endothelial migration (rolling, firm adhesion, trans migration)
• segmented nucleus
• granules containing an array of preformed anti-pathogen mediators

Question 6

% of circulating leukocytes that are neutrophils?

Answer 6

In humans = 70%

Mice = 10-25%

Question 7

Neutrophil degranulation

Answer 7

• membrane receptors that detect signals of tissue injury and infection
• nucleotides, bioactive amines and ions
• adhesion molecules, PMPs, kinocidins, mitogenic factors, coagulation factors, protease inhibitors
• proteases, glycosidases

Question 8

Neutrophil phagocytosis

Answer 8

• bacterium is phagocytosed by neutrophil
• phagosome fuses with azurophilic and specific granules
• pH of phagosome rises, antimicrobial response is activated, and bacterium is killed
• pH of phagosome decreases, fusion with lysosomes allows acid hydrolases to degrade the bacterium completely
• neutrophil dies by apoptosis and is phagocytosed by macrophage

Question 9

Neutrophil Netosis

Answer 9

• the DNA when released is a 3D structure many times the size of the original cell
• the DNA acts as a net trapping bacteria

Question 10

Leukocytes -WBCs

Answer 10

-Eosinophil, basophil, neutrophil (Granulocytes)

Question 11

Monocyte:

Answer 11

Dendrtitic cell and Macrophage precursor

Question 12

Lymphocyte:

Answer 12

Adaptive immune system

Question 13

Cytokines:

Answer 13

-family of secreted proteins(includes chemokines, interferons, interleukins, growth factors)

Question 14

Cytokines:

Answer 14

• Can be secreted by cells of the immune system and also stromal cells
• responding cells carry specific receptor that recognises cytokine

Question 15

Cytokines affects on cell behaviour:

Answer 15

• life span
• motility
• killing capacity (enhance/reduce)
• repair programmes
• proliferation

Question 16

Chemokines

Answer 16

-chemotaxis*****

Question 17

Cells of the adaptive immune system

Answer 17

• dendtritic cells
• T cells
• B cells
• become activated in lymphnodes