22. Mucosal Immunity Flashcards Preview

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Flashcards in 22. Mucosal Immunity Deck (55):
1

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

Lower
IgG

2

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

Upper (aerobic bacteria)
IgA

3

What structures are included in waldeyer's ring?

Palatine tonsils
Tubal tonsils
Adenoid
Lingual tonsil

4

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

Unencapsulated

5

What epithelium is present in the oral cavity

Partially keritonized stratified squamous

6

What epithelium is present in the esophagus

Non-keritonized stratified squamous

7

What epithelium is present in the stomach

Simple columnar with goblet cells

8

What epithelium is present in the small intestine

Simple columnar with goblet cells, crypts, and villi

9

What epithelium is present in the colon

Simple columnar with crypts

10

What epithelium is present in the anus

Non-keritonized stratified

11

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

In the lamina propria (right under the epithelium)

12

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

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

13

Where can antigens drain from the lamina propria folicles?

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

14

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

Idiopathic intussusception

15

What lies over Peyer's patches in the ileum?

Follicle-associated epithelium

16

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

M cells

17

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

BCR
TCR

18

Organization of a Peyers patch is similar to that of:

Lymph node, except it is not encapsulated

19

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

Claudins
Occludins

20

What protein is involved in adherens junctions between epithelial cells?

E-cadherin

21

What are three kinds of APCs?

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

22

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?

Immune response
Tolerance response--naive T cell becomes a Treg cell

23

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?

NLR
TLR

24

What are genes activated downstream of pattern recognition receptors?

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

25

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

alpha4beta7 integrin
CCR9

26

What do alpha4beta7 integrin and CCR9 bind?

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

27

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

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

28

What cytokine is produced by Th1?

IFN-y

29

What cytokines are produced by Th2?

IL-4
IL-5
IL-13

30

What cytokine is produced by Th17?

IL-17

31

What induces differentiation of:
Th1
Th2
Th17

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

32

The following are for host defense against:
- Th1
- Th2
- Th17

Intracellular microbes
Helminthic parasites
Extracellular bacteria and fungi

33

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

Antibody secretion
Class switching
Affinity maturation

34

What is complement?

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

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

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

What complement pathway is particularly important in the gut?

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

T dependent class switching to IgA

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

T-independent class switching to IgA

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

IgA as a dimeric protein held together by:

The J chain

40

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

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

What is the difference between an immunogen and an antigen

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

42

Effect of size on immunogenicity

Large: increased
Small: decreased

43

Effect of dose on immunogenicity

Intermediate: increased
High or low: decreased

44

Effect of route on immunogenicity

SubQ>intraperitoneal>IV or IG

45

Effect of composition on immunogenicity

Complex: increased
Simple: decreased

46

What is hypersensitivity?

Excessive or aberrant immune responses following challenge with antigen

47

What are two things that hypersensitivity is caused by?

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

What are the 4 types of hypersensitivity?

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

49

Mechanism of tissue injury in type I hypersensitivity?

Mast cells and eosinophils and their mediators
Inflammation

50

Mechanism of tissue injury in type II hypersensitivity?

Opsonization/phagocytosis
Complement and Fc recruitment of leukocytes

51

Mechanism of tissue injury in type III hypersensitivity?

Complement and Fc recruitment of leukocytes

52

Mechanism of tissue injury in type IV hypersensitivity?

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

53

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

Tolerance

54

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

T cell tolerance is long-lived
B cell tolerance is short-lived, less complete

55

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