141b - Mucosal Immunology

Question 1

Where in the GI tract are paneth cells most abundant?

Answer 1

Small intestine, at the bases of crypts

(There are none in the large intestine)

Question 2

What roles do epithelial cells paly in innate immunity? (3)

Answer 2

• Physical barrier
• Immune recognition
• Pattern recognition (ex: TLRs that recognize PAMPs expressed by bacteria, viral species)

Question 3

Each of the following mechanisms have been suggested to play a role in the pathogenesis of this inflammatory bowel disease except:

1. Increased intestinal permeability
2. Expression of susceptibility genes
3. Impaired IgA production
4. Impaired innate immunity

Answer 3

c. Impaired IgA production

Question 4

Intestinal epithelial cells serve a immunological function by

1. Initiating innate immune responses
2. Serving as a physical barrier that excludes antigens
3. Transport and secrete IgA
4. All of the above

Answer 4

d. All of the above

Question 5

Which part of the GI tract preferentially binds flagellated bacteria?

Answer 5

Large intestine

• More goblet cells = more mucin production

Question 6

All of the following are unique properties of the gut associated lymphoid tissue (GALT) except

1. Microfold cells
2. Initiates both innate and adaptive immune responses
3. Induction immunological tolerance
4. Preferential production of IgA

Answer 6

b. Initiates both innate and adaptive immune responses

(Note: Microfold cell = M cell)

Question 7

Where do GALT effector cells reside?

Answer 7

Lamina propria

Intraepithelial cell compartment

(basically, all immune system like cells are in lamina propia | remember the macrophages in Whipple’s)

Question 8

Which dendritic cell subsets promote oral tolerance? (2)

Answer 8

CD 103+

CD 11b+

Question 9

After a lymphyocyte is educated in a Peyer’s Patch (lympoid follicle), where does it end up?

Answer 9

Ends up in the lamina propria (effector site)

• After going from Peyer’s patch -> lymph system -> blood stream
  
  • They find their way home!
  • This process is a treatment target for IBD (vedolizumab)

Question 10

Which cells produce trefoil peptides?

What is their function?

Answer 10

Goblet cells

Antimicrobial

Question 11

What is the function of Peyers Patches?

Answer 11

Peyers patches contain lymphoid follicles - this is where immune cells are educated

Question 12

What is the function of Peyers Patches?

Answer 12

Peyers patches contain lymphoid follicles - this is where immune cells are educated

• Antigen sampled from lumen
• Presented to immune cells in the lymphoid follicle (in Peyer’s patches)
• Immune cells (lymphocytes) are educated
  
  • B cells from immature B cells -> Plasma cells
  • T cells -> different phenotypes
• Migrate to mesenteric lymph nodes
• Blood stream
• Home back to GI tract
• Reside in the lamina propria: effector sites

Question 13

What functions of IgA are important for preventing autoimmune/allergy disorders? (3)

Answer 13

IgA functions to…

• Limit the innate immune response
• Modulate intestinal regulatory T cells
• Regulate the commensal gut flora

Question 14

Microbiota signaling to the dendritic T cells is important for several immune functions.

What are they? (4)

Answer 14

• IL-10 synthesis
• T-regulatory cell proliferation
• Short-chain fatty acid production
• Th-2 inhibition

Basically, a healthy microbiome is important for normal immune function!