Mucosal Immunology

Question 1

what are cytokines?

Answer 1

chemical mediators that regulate immune response
- key communicators
- there’s lots of them (from different families)
- small proteins made up of 2 subunits

Question 2

what is major site of host-environment interaction?

Answer 2

GI tract

Question 3

what is gastrointestinal epithelial barrier made up of?

Answer 3

single layer of cells with different phenotypes
- physical barrier between host & environment

Question 4

what does gastrointestinal epithelial barrier do to retain continuity?

Answer 4

rapid restitution (repairs itself every few days)

Question 5

what does gastrointestinal epithelial barrier have selective permeability for?

Answer 5

water, ions, nutrients

Question 6

how does gastrointestinal epithelial barrier help with innate immunity?

Answer 6

has secretory function -> cytokines, antimicrobial peptides, MUC proteins which secrete into lumen to keep bacteria at bay

Question 7

what are MUC proteins?

Answer 7

form protein matrix to make mucus barrier layer

Question 8

what are at base at base of crypts?

Answer 8

stem cells that based on chemical signals are able to become special epithelial cells & move up crypt toward gut
- Lgr5 + cells
- proliferation & differentiation as they move up and then cell shedding at tip

Question 9

what is autophagy?

Answer 9

cell function where you take dead & dying cells & kill in controlled way

Question 10

where are immune cells in gut mucosa?

Answer 10

lamina propria

Question 11

what is unique to gut mucosa?

Answer 11

• develop self-tolerance (non-responsiveness to self antigens)
• develop exogenous tolerance (Non-responsiveness to an enormous array of newly encountered environmental antigens (Food and Microbes))
• develop an effective immune response

Question 12

how does immune system impact intestinal epithelial cells?

Answer 12

• promote barrier repair e.g. IL 22
• Promote mucin production and AMP secretion eg ILC derived IL-13 on goblet cells
• Macrophage and Treg derived mediators – stimulate repair
• Impact on permeability

Question 13

why is menteric lymph nodes important part of the gut?

Answer 13

Important for immune responses to commensal bacteria (tolerance) and pathogens (active immunity)

• Allow efficient sampling of particulate antigens and deliver to APC

Question 14

what are T regs required for?

Answer 14

maintaining immune homeostasis & tolerance