Mucosal Immunity

Question 1

Amount that microvili increase the intestinal surface area by.

Answer 1

30-fold.

Question 2

Factors secreted by enterocytes

Answer 2

TGF-beta, chemokines, defensins

Question 3

Factors secreted by goblet cells

Answer 3

Mucins, lysozyme, lactoferrin

Question 4

Factors secreted by paneth cells

Answer 4

Defensins

Question 5

Paneth cell location

Answer 5

Base of vili

Question 6

Surface area of small intestine

Answer 6

250 square meters

Question 7

Number of resident bacterial species in GIT

Answer 7

700 - 1000

Question 8

Number of bacteria in GIT

Answer 8

~10^14

Question 9

Glycocalyx

Answer 9

Mucus layer that associates with glycoprotein and polysaccharide complex.

On enterocytes.

Keeps bacteria away from epithelial surface.

Question 10

Innate defence mechanisms of the gut

Answer 10

Peristalsis
Acid
Glycocalyx
Tight junctions between cells
Regular replacement of enterocytes
Cytokines and chemokines secreted by cells
Lymphocytes, macrophages, dendritic cells

Question 11

Spleen

Answer 11

Receives antigens from the blood.

Part of systemic immune system.

Question 12

Mucosal lymphoid tissues

Answer 12

Tonsils, adenoid, appendix, Peyers patches, large intestine.

Question 13

Mucosal immune system antigen access

Answer 13

Sampled directly from gut lumen.

Question 14

Scattered lymphoid cells

Answer 14

Effector sites

Question 15

Organised lymphoid tissues

Answer 15

Inductive sites

Question 16

Blood vessels that run through Peyers patches, mesenteric lymph nodes.

Answer 16

High endothelial venules

Question 17

Cells that sit on top of Peyers patches

Answer 17

M cells

Question 18

Area beneath epithelial layer on Peyers patches, contains dendritic cells

Answer 18

Sub-epithelial dome

Question 19

Where Peyers patches drain to.

Answer 19

Mesenteric lymph node.

Question 20

Cells from which M cells have differentiated

Answer 20

Endothelial cells

Question 21

Features of M cells

Answer 21

No microvili.
Don’t secrete mucus.
Controlled uptake of antigens.
Transport antigens to sub-epithelial space.
Do not express MHC class II
Located directly over organised lymphoid tissue.

Question 22

Location of M cells

Answer 22

Directly over organised lymph tissue in mucosal immune system.

Question 23

Classes of MHC on M cells

Answer 23

MHC class I.
No MHC class II.

Question 24

Two methods of antigen access to mesenteric lymph nodes

Answer 24

1) Via microfold cells.

2) Via dendritic cells, which migrate from vili to MLN.

Question 25

Mucosal dendritic cell specialisations

Answer 25

Secrete cytokines to skew T response to Treg, Th2 (TGF-beta). Bias B cell isotype to IgA. Induce alpha 4 beta 7 expression on activated lymphocytes.

Question 26

Integrin alpha-4 beta-7 ligand.

Answer 26

MAdCAM1

Question 27

Activation of naive lymphocytes occurs in:

Answer 27

Peyers patches - APCs take up antigen delivered by M cells. Mesenteric lymph nodes - Dendritic cells migrate from Peyers patches, lamina propria, present antigens.

Question 28

APC uptake of antigens occurs in:

Answer 28

Lamina propria - DSs directly sample lumen contents. Peyers patches - DSs take up antigens let in by M cells.

Question 29

Anti-mesenteric border

Answer 29

Opposite side to luminal side.

Question 30

Where is MAdCAM1 expressed?

Answer 30

Endothelial cells of high endothelial venules.

Question 31

Once activated in mesenteric lymph nodes, T and B cells...

Answer 31

Enter bloodstream, return to effector sites. | EG: Lamina propria

Question 32

T-cell homing receptors into Peyers patches

Answer 32

CCR 7, L-selectin

Question 33

Where do mesenteric lymph nodes drain?

Answer 33

Thoracic duct.

Question 34

Activated T-cell homing receptors for small intestine

Answer 34

CCR9, alpha-4 beta-7 integrin.

Question 35

CCR9 ligand.

Answer 35

CCL25.

Question 36

CCL25 location

Answer 36

Small intestine epithelium.

Question 37

CCR10 ligand.

Answer 37

CCL28.

Question 38

CCL28 location.

Answer 38

Epithelium of large intestine.

Question 39

MAdCAM1 sites of expression.

Answer 39

Many mucosal sites.

Question 40

TGF beta induces particular types of: 1) T cells 2) Antibodies

Answer 40

1) Treg, Th2 | 2) IgA.

Question 41

Proteins associated with IgA dimers in mucosal tissue.

Answer 41

Secretory component. | J-chain.

Question 42

Amount of IgA secreted per day.

Answer 42

3-5g.

Question 43

pIgR location.

Answer 43

Basolateral face of intestinal epithelial cell.

Question 44

IgA receptor on basolateral surface of epithelial cells.

Answer 44

pIgR.

Question 45

pIgR

Answer 45

Polymeric IgA Receptor.

Question 46

Origin of secretory component.

Answer 46

pIgR on epithelial cells. Part of pIgR cleaved off in the lumen, this forms the secretory component.

Question 47

Functions of sIgA: 1) 2)

Answer 47

1) Blocks toxin attachment. 2) Blocks epithelial attachment. Serves these functions in lumen, intracellularly and in lamina propria.

Question 48

Properties of sIgA: 1) 2) 3)

Answer 48

1) Doesn't activate complement cascade, to reduce inflammation. 2) Weak opsonin. 3) Long half life - secretory component protects against enzymatic degradation.

Question 49

Respiratory tract inductive sites. 1) 2)

Answer 49

1) Adenoids. | 2) Tonsils.

Question 50

Secretions of alveolar epithelium.

Answer 50

Surfactant fluid. | NOT mucus.

Question 51

Surfactant fluid properties.

Answer 51

Antimicrobial. SP-A, SP-B, SP-D.

Question 52

Respiratory tract effector sites: 1) 2) 3)

Answer 52

1) Salivary glands. 2) Lacrimal glands. 3) Bronchus.

Question 53

Ligands in small intestine for a-4 b-7 and CCR9 of activated T cells

Answer 53

a-4 b-7 - E-caderhin | CCR9 - CCL25

Question 54

Ligands in large intestine for a-4 b-7 and CCR10 of activated t cells

Answer 54

a-4 b-7 - E-cadherin | CCR10 - CCL28