PMI02-2006 Mucosal Immunity

Question 1

What is a mucosal surface?

Answer 1

Secretory or absorptive surface

Question 2

What are the differences between systemic and mucosal environment?

Answer 2

Systemic environment is contained, sterile and encounters undefined antigens rarely
Mucosal environment is exposed, non-sterile and encounters undefined antigens continuously

Question 3

What is the purpose of mucosal immunity?

Answer 3

Protects against pathogens but prevents hypersensitivity to foods/ commensal organisms
If mucosal response broke down, there would be inflammatory response to every antigen that enters to body.

Question 4

What is the non-immunological protection?

Answer 4

Natural acids such as gastric acid
Tight junctions make it harder for pathogens to peentrate
Mucins
Microvilli and cilia prevents microbes binding to epithelial
Rate of epithelial turnover and peristalsis increase in response to infection
Porteolysis occurs by enzymes

Question 5

What is the immunological protection?

Answer 5

AMPs
Secretory IgM and IgA
Intraepithelial lymphocytes and phagocytes

Question 6

What is an inductive site?

Answer 6

The site where the immune response is being induced

Question 7

What is an effector site?

Answer 7

Effector sites is where the immune response is having its impact

Question 8

What are the inductive and effector sites collectively called in mucosa?

Answer 8

Mucosal associated Lymphoid Tissue

Question 9

What are Peyers Patches?

Answer 9

Secondary lymph nodes assoc gut
50% B cells, 30% T cells, 8% macrophages
Few plasma cells
Connected to the lymphatic system via an efferent vessel

Question 10

What are isolated lymphoid follicles?

Answer 10

induced by products of commensal gut bacteria

More ILFs than Peters patches

Question 11

What are M cells?

Answer 11

Microfold cells
Antigens are transports across the m cell in vesicles to the basal surface
At the basal surface, antigens are released and bound by dendritic cells to be presented to T cells

Question 12

What occurs when T and B cells are activated in peters patches?

Answer 12

T and B switch expression from L-selectin and CCR7 to a4b7 intern and CCR9
B cells class switch from IgM to IgA

Question 13

What are the 2 compartments of the mucosal immune system?

Answer 13

Lamina propria

Epithelial cells

Question 14

What cells are within the lamina propria?

Answer 14

Plasma cells, dendritic cells, IgA, mast cells, macrophages and T cels

Question 15

What cells are within the epithelia?

Answer 15

Dendritic cells
Langerhans
Intraepithelial lymphocytes

Question 16

What are the lamina propria T cells?

Answer 16

Majority are CD4+ cells, in ratio of 2:1 with CD4:CD8

Question 17

What do lamina propria T cells express?

Answer 17

a4b7 integrins, which bind the MadCam ligand, which secretes cytokines

Question 18

What do Treg do?

Answer 18

Supresses immune activity via IL-10 or TGF-B

Question 19

What do Th1 do?

Answer 19

Activates macrophages via IFN-Y

Question 20

What does Th2 do?

Answer 20

Induces B cell class switching to IgA via IL-5

Question 21

What does Th17 do?

Answer 21

Maintains epithelial barrier function via IL-22 and activates neutrophils through IL-17

Question 22

What are intraepithelial lymphocytes?

Answer 22

Majority are CD8+

These are made up of 2 alpha chains as oppose to others that are 1 alpha and 1 beta

Question 23

What do intraepithelial T cells express?

Answer 23

aeB7 that binds to E-cadherin on epithelial cells