2: Immunology - Mucosal immune system

Question 1

Which lymph nodes are found in the gut?

Answer 1

Peyer’s patches

Question 2

Which component of Peyer’s patches have ruffled membranes?

What is their function?

Answer 2

M cells

Antigen sampling and absorption

Question 3

By which two processes do M cells take up antigen in the Peyer’s patches?

Answer 3

Endocytosis

Phagocytosis

Question 4

Which immune cells bind to the antigens absorbed through M cells and present them to other immune cells?

Answer 4

Dendritic cells

Question 5

Which immune cells can project themselves across the epithelial membrane of the gut to sample antigen in the gut lumen?

Answer 5

Dendritic cells

Question 6

Which types of T cell are found in the epithelium of the gut?

Answer 6

Cytotoxic T cells (CD8+)

Question 7

Which types of T cell are found in the lamina propria of gut cells?

Answer 7

Helper T cells (CD4+)

Question 8

Which cells, found in the lamina propria, are activated by dendritic cells presenting antigen?

Answer 8

T cells

Question 9

How do T cells reach the basolateral membrane of gut cells?

Answer 9

Bloodstream

Question 10

Through which lymphatic vessel do activated T cells have to drain to reach the bloodstream?

Answer 10

Thoracic duct

Question 11

What is an MA?

Answer 11

Molecular address signal - binds to effector T cells which need to return to that area in the gut

Question 12

Which signals direct migration of T cells through the gut epithelium?

Answer 12

Chemokines

Question 13

Adhesion molecules ___ T cells to the gut epithelium.

T cells then migrate through the epithelium by following a ___ gradient.

Answer 13

anchor

chemokine

Question 14

Which disease causes individuals to initially lose up to 70% of memory T cells in their gut?

Answer 14

HIV

Question 15

How are memory cells transferred from mother to child?

Which type of immunity is this?

Answer 15

Breasfeeding

Passive immunity

Question 16

Which antibody is most common in the intestinal mucosa?

Answer 16

IgA

Question 17

Which antibody is most common in the systemic immune response?

Answer 17

IgG

Question 18

Which antibody is the first to appear, but not the most abundant, in the intestinal and systemic immune responses?

Answer 18

IgM

Question 19

Which type of antibody is most abundant in breast milk?

Answer 19

IgA

Question 20

IgA is a (monomer / dimer).

Answer 20

dimer

Question 21

Some immune cells in the gut serve only to produce (IgA / IgM), all the time.

Answer 21

IgA

Question 22

Where are IgA-secreting cells found?

Answer 22

Lamina propria

i.e not the epithelium

Question 23

How does IgA enter epithelial cells from the lamina propria?

Answer 23

Endocytosis

Question 24

After passing from the lamina propria to the epithelium, where is IgA secreted?

By which process?

Answer 24

Gut lumen

Exocytosis

Question 25

What does **secretory component** do for IgA?

Answer 25

**Allows it to persist in the gut lumen for a while without being digested by proteolytic enzymes**

Question 26

IgA stops ___ and ___ from binding to the gut epithelium.

Answer 26

**toxins** **pathogens**

Question 27

Apart from preventing pathogen/toxin binding, IgA can ___ antigens by internalising them in a vesicle.

Answer 27

**neutralise**

Question 28

While being excreted from the gut by exocytosis, IgA can ___ pathogens back to the gut lumen.

Answer 28

**export**

Question 29

Which immunoglobulin is very important in protecting the gut epithelium?

Answer 29

**IgA**

Question 30

What are **intraepithelial lymphocytes**?

Answer 30

Mainly **cytotoxic T cells** (CD8+)

Question 31

What do **intraepithelial lymphocytes** do?

Answer 31

**Kill infected** (virally or otherwise) **epithelial cells** from the basolateral side

Question 32

What protein **displays** self antigen on the surface of all body cells so that they aren't killed off by immune cells?

Answer 32

**MHC Class I**

Question 33

The immune response to protein is **(stimulated / inhibited)** when that protein is administered orally.

Answer 33

**inhibited**

Question 34

The immune system is **hyporesponsive** to antigens which are ingested with \_\_\_.

Answer 34

**food**

Question 35

When exposed to **commensal bacteria**, dendritic cell maturation is **(inhibited / stimulated)**.

Answer 35

**inhibited** hyporesponsiveness of immune system in response to food

Question 36

When exposed to **invasive microorganisms**, dendritic cells are **(inhibited / activated)**.

Answer 36

activated

Question 37

What four diseases can occur when the mucosal immune system is dysregulated?

Answer 37

**Primary immunodeficiency** **Allergy** **Coeliac disease** **IBD**