22. Mucosal Immunity

Question 1

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

Answer 1

Lower

IgG

Question 2

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

Answer 2

Upper (aerobic bacteria)

IgA

Question 3

What structures are included in waldeyer’s ring?

Answer 3

Palatine tonsils
Tubal tonsils
Adenoid
Lingual tonsil

Question 4

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

Answer 4

Unencapsulated

Question 5

What epithelium is present in the oral cavity

Answer 5

Partially keritonized stratified squamous

Question 6

What epithelium is present in the esophagus

Answer 6

Non-keritonized stratified squamous

Question 7

What epithelium is present in the stomach

Answer 7

Simple columnar with goblet cells

Question 8

What epithelium is present in the small intestine

Answer 8

Simple columnar with goblet cells, crypts, and villi

Question 9

What epithelium is present in the colon

Answer 9

Simple columnar with crypts

Question 10

What epithelium is present in the anus

Answer 10

Non-keritonized stratified

Question 11

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

Answer 11

In the lamina propria (right under the epithelium)

Question 12

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

Answer 12

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

Question 13

Where can antigens drain from the lamina propria folicles?

Answer 13

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

Question 14

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

Answer 14

Idiopathic intussusception

Question 15

What lies over Peyer’s patches in the ileum?

Answer 15

Follicle-associated epithelium

Question 16

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

Answer 16

M cells

Question 17

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

Answer 17

BCR

TCR

Question 18

Organization of a Peyers patch is similar to that of:

Answer 18

Lymph node, except it is not encapsulated

Question 19

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

Answer 19

Claudins

Occludins

Question 20

What protein is involved in adherens junctions between epithelial cells?

Answer 20

E-cadherin

Question 21

What are three kinds of APCs?

Answer 21

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

Question 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?

Answer 22

Immune response

Tolerance response–naive T cell becomes a Treg cell

Question 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?

Answer 23

NLR

TLR

Question 24

What are genes activated downstream of pattern recognition receptors?

Answer 24

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

Question 25

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

Answer 25

alpha4beta7 integrin | CCR9

Question 26

What do alpha4beta7 integrin and CCR9 bind?

Answer 26

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

Question 27

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

Answer 27

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

Question 28

What cytokine is produced by Th1?

Answer 28

IFN-y

Question 29

What cytokines are produced by Th2?

Answer 29

IL-4 IL-5 IL-13

Question 30

What cytokine is produced by Th17?

Answer 30

IL-17

Question 31

What induces differentiation of: Th1 Th2 Th17

Answer 31

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

Question 32

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

Answer 32

Intracellular microbes Helminthic parasites Extracellular bacteria and fungi

Question 33

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

Answer 33

Antibody secretion Class switching Affinity maturation

Question 34

What is complement?

Answer 34

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

Question 35

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

Answer 35

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

Question 36

What complement pathway is particularly important in the gut?

Answer 36

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

Question 37

T dependent class switching to IgA

Answer 37

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

Question 38

T-independent class switching to IgA

Answer 38

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

Question 39

IgA as a dimeric protein held together by:

Answer 39

The J chain

Question 40

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

Answer 40

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

Question 41

What is the difference between an immunogen and an antigen

Answer 41

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

Question 42

Effect of size on immunogenicity

Answer 42

Large: increased Small: decreased

Question 43

Effect of dose on immunogenicity

Answer 43

Intermediate: increased | High or low: decreased

Question 44

Effect of route on immunogenicity

Answer 44

SubQ>intraperitoneal>IV or IG

Question 45

Effect of composition on immunogenicity

Answer 45

Complex: increased Simple: decreased

Question 46

What is hypersensitivity?

Answer 46

Excessive or aberrant immune responses following challenge with antigen

Question 47

What are two things that hypersensitivity is caused by?

Answer 47

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

Question 48

What are the 4 types of hypersensitivity?

Answer 48

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

Question 49

Mechanism of tissue injury in type I hypersensitivity?

Answer 49

Mast cells and eosinophils and their mediators | Inflammation

Question 50

Mechanism of tissue injury in type II hypersensitivity?

Answer 50

Opsonization/phagocytosis | Complement and Fc recruitment of leukocytes

Question 51

Mechanism of tissue injury in type III hypersensitivity?

Answer 51

Complement and Fc recruitment of leukocytes

Question 52

Mechanism of tissue injury in type IV hypersensitivity?

Answer 52

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

Question 53

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

Answer 53

Tolerance

Question 54

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

Answer 54

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

Question 55

***STOPPED BEFORE THE LAST FEW

Answer 55

SLIDES