Final Review Questions

Question 1

What is Fc region?

Answer 1

Part of the antibody that interacts with FcR, and is responsible for performing the effector function of the ab

Question 2

Why are there no Fc receptors for IgM?

Answer 2

IgM is too large to leave the blood, and too large to be phagocytosed, and there are no FcR for IgM

Question 3

Which isotypes of immunoglobulin can be opsonins?

Answer 3

IgM: activates complement, and C3b acts as the opsonin
IgG: binds directly to an Fc receptore

Question 4

Would IgG treated with papain be capable of:
A) neutralization
B) opsonization
C) transport into tissues

Answer 4

A) yes, Fab portion is needed only
B) no: Fab can bind, but without the Fc region attached it cannot perform effector function
C) no: Fc region can bind to FcR, but needs FAb to bind to cell that will be transported

Question 5

How are intestinal macrophages like other mps? Different?

Answer 5

• can phagocytose, do not cause inflammation, ROS, have CD14, Fc, or B7

Question 6

What kind of cell secretes IL-10 in the gut?

Answer 6

DC

Question 7

What kind of T cells are activated when there is no infection in the gut?

Answer 7

FoxP3+ T reg cells

Question 8

Why can mucosal tissues respond to infection sooner than non-mucosal tissues?

Answer 8

Secondary lymphoid tissues continuously sample lumen contents, and live just under the surface
- non-mucosal tissues are only populated with B/T cells during infection

Question 9

What kinds of effector cells are in the mucosal tissues?

Answer 9

Th1, Th17 CD4 T, some DC mp eosinophils

Question 10

What happens when a commensal bacteria crosses the epithelial barrier?

Answer 10

-treated as foreign: chemokines/cytokines IL-1/6
- intestinal mps engulf without inflammation (anger management classes)
- nps, monocytes, eosinophils recruited from the blood
- if not cleared, adaptive response is generated from mesentaric lymph node (regular inflammatory cells)

Question 11

What are commensals?

Answer 11

• resident bacteria that have a symbiotic relationship with GI tract
  1. Keep other pathogens at bay
  2. Digest vitamins and minerals
  3. Digest plant fibers

Question 12

What type of immune response do commensals normally generate?

Answer 12

STIMULATE NON-INFLAMMATORY RESPONSES
- Stimulate the activation of Treg cells that secrete IL-10
- when other immune cells recognize antigen, they do not develop inflammatory response

Question 13

What is transcytosis? Ex.

Answer 13

Macromolecules are transported across cell
- ex: Ag moving from lumen of the gut through M cell
- ex: Ag moving across gut epithelia

Question 14

How do the bacteria in yogurt help your innate immunity in the gut?

Answer 14

Bacteria occupy space, makes it hard for others to colonize, can produce anti-microbial substances

Question 15

What are M cells?

Answer 15

MICROFOLD cells:
- folded luminal surface on cell, no mucus