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GI > 22. Mucosal Immunity > Flashcards

22. Mucosal Immunity Flashcards

1
Q

What part of the nasopharyngeal tract is sterile? What Ig is dominant?

A

Lower

IgG

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2
Q

What part of the nasopharyngeal tract is colonized? What Ig is dominant?

A

Upper (aerobic bacteria)

IgA

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3
Q

What structures are included in waldeyer’s ring?

A

Palatine tonsils
Tubal tonsils
Adenoid
Lingual tonsil

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4
Q

All of the MALT tissues are _____, excluding the mesenteric tissues

A

Unencapsulated

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5
Q

What epithelium is present in the oral cavity

A

Partially keritonized stratified squamous

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6
Q

What epithelium is present in the esophagus

A

Non-keritonized stratified squamous

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7
Q

What epithelium is present in the stomach

A

Simple columnar with goblet cells

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8
Q

What epithelium is present in the small intestine

A

Simple columnar with goblet cells, crypts, and villi

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9
Q

What epithelium is present in the colon

A

Simple columnar with crypts

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10
Q

What epithelium is present in the anus

A

Non-keritonized stratified

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11
Q

Where in the esophagus do immune cells accumulate with physiologic inflammation?

A

In the lamina propria (right under the epithelium)

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12
Q

Once antigens enter lacteals in the villi, where do they drain?

A

Lamina propria follicles (span the lamina propria and may extend into the submucosa)

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13
Q

Where can antigens drain from the lamina propria folicles?

A

Mesenteric lymph nodes (outside the mucosa), not a part of MALT

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14
Q

What pathology is hypertrophy of ileal Peyer’s patches associated with?

A

Idiopathic intussusception

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15
Q

What lies over Peyer’s patches in the ileum?

A

Follicle-associated epithelium

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16
Q

What is the distinctive cell type in follicle-associated epithelium?

A

M cells

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17
Q

Once antigens enter Peyer’s patches, what receptor recognizes free antigen? Antigen presented by APCS?

A

BCR

TCR

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18
Q

Organization of a Peyers patch is similar to that of:

A

Lymph node, except it is not encapsulated

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19
Q

What are the main proteins involved in tight junctions between epithelial cells?

A

Claudins

Occludins

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20
Q

What protein is involved in adherens junctions between epithelial cells?

A

E-cadherin

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21
Q

What are three kinds of APCs?

A
  1. DC
  2. Activated macrophages
  3. Follicular DCs (germinal centers)
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22
Q

A DC presents an antigen to a T cell.

  • What happens in the presence of TGF-beta and IL-6?
  • What happens in the presence of TGF-beta and RA?
A

Immune response

Tolerance response–naive T cell becomes a Treg cell

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23
Q

What pattern recognition receptor is cytoplasmic (in intestinal epithelial cells)? Which one is expressed on the basolateral surface of the cell, facing the extracellular env?

A

NLR

TLR

24
Q

What are genes activated downstream of pattern recognition receptors?

A 
Cytokines: TNF, IL-1, IL-12
Chemokines
E-selectin
Costimulatory molecules
Antiviral cytokines: IFNalpha/beta
25
Q

What are the two gut homing molecules that IgA secreting B cells and effector T cells express?

A

alpha4beta7 integrin

CCR9

26
Q

What do alpha4beta7 integrin and CCR9 bind?

A

alpha4beta7: MADCAM (on gut endothelial cells)
CCR9: CCL25

27
Q

What do DCs in Peyers patches or mesenteric lymph nodes produce to induce the expression of CCR9 and alpha4beta7?

A

Retinoic acid

**intestinal epithelial cells also express retinal dehydrogenase, leading to elevated retenoic acid in gut tissues

28
Q

What cytokine is produced by Th1?

A

IFN-y

29
Q

What cytokines are produced by Th2?

A

IL-4
IL-5
IL-13

30
Q

What cytokine is produced by Th17?

A

IL-17

31
Q

What induces differentiation of:
Th1
Th2
Th17

A

IL-12, IFN-y
IL-4
IL-6, IL-23

32
Q

The following are for host defense against:

  • Th1
  • Th2
  • Th17
A

Intracellular microbes
Helminthic parasites
Extracellular bacteria and fungi

33
Q

What are the three key things that are going on in the germinal center of follicles?

A

Antibody secretion
Class switching
Affinity maturation

34
Q

What is complement?

A

System of serum and cell surface proteins that interact with one another and other molecules of the immune response to generate effectors of innate and adaptive immune systems

35
Q

What is the first step of all three complement pathways? Next steps?

A

Binding of complement to the microbial cell surface or a surface antibody
Formation of C3 convertase
Cleavage of C3
Binding of C3 to the cell surface

36
Q

What complement pathway is particularly important in the gut?

A

Lectin pathway: gut has more bacteria than cells in the body and mannose is on the bacterial surface
Mannose binding lectin binds mannose to start cascade

37
Q

T dependent class switching to IgA

A
  1. DCs in peyers patches present antigen to naive T cells to make Th1 cells
  2. CD40L on Th1 and TBFbeta from DC activate naive B cell to make IgA
38
Q

T-independent class switching to IgA

A
  1. TLRs expressed on DCs stimulate the release of TGFbeta, RA (and APRIL, BAFF, IL-6) from the DC
  2. B cell stimulated to produce IgA
39
Q

IgA as a dimeric protein held together by:

A

The J chain

40
Q

How does IgA get transported from the lamina propria across the mucosal epithelial cell to the lumen?

A

J chain of IgA bound by poly-Ig receptor
Poly-Ig receptor bound to IgA is endocytosed
Proteolytic cleavage allows freeing of IgA into the lumen

41
Q

What is the difference between an immunogen and an antigen

A

Immunogen: antigen that induces an immune response
Antigen: any molecule that is bound by an antibody or T cells

42
Q

Effect of size on immunogenicity

A

Large: increased
Small: decreased

43
Q

Effect of dose on immunogenicity

A

Intermediate: increased

High or low: decreased

44
Q

Effect of route on immunogenicity

A

SubQ>intraperitoneal>IV or IG

45
Q

Effect of composition on immunogenicity

A

Complex: increased
Simple: decreased

46
Q

What is hypersensitivity?

A

Excessive or aberrant immune responses following challenge with antigen

47
Q

What are two things that hypersensitivity is caused by?

A
  1. Dysregulated or uncontrolled response to foreign antigens resulting in tissue damage and injury
  2. Failure or self-tolerance followed by immune responses directed against “self” antigens
48
Q

What are the 4 types of hypersensitivity?

A

I: IgE (immidiate)
II: IgG/IgM (antibody mediated)
III: Immune complex mediated
IV: T cell mediated

49
Q

Mechanism of tissue injury in type I hypersensitivity?

A

Mast cells and eosinophils and their mediators

Inflammation

50
Q

Mechanism of tissue injury in type II hypersensitivity?

A

Opsonization/phagocytosis

Complement and Fc recruitment of leukocytes

51
Q

Mechanism of tissue injury in type III hypersensitivity?

A

Complement and Fc recruitment of leukocytes

52
Q

Mechanism of tissue injury in type IV hypersensitivity?

A

CD4: macrophage activation, infl
CD8: target cell killing, inflammation

53
Q

What is the name for the specific unresponsiveness of the normal immune system to an individuals own self antigens

A

Tolerance

54
Q

How does tolereance in the T and B cell compartments differ?

A

T cell tolerance is long-lived

B cell tolerance is short-lived, less complete

55
Q

***STOPPED BEFORE THE LAST FEW

A

SLIDES

GI (28 decks)

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