Mucosal Immunology and Food Allergy

Question 1

What is present within microvilli?

Answer 1

Artery, vein, and lymphatic projections.

Question 2

Purpose of microvillous lymphatic projections

Answer 2

Important in trafficking immune cells from draining lymph node

Question 3

Paneth Cells

Answer 3

Produce anti-microbial substances

Question 4

Oral tolerance

Answer 4

Oral feeding of antigen to tolerize, subcutaneous injection of antigen and adjuvant leads to tolerance.

Question 5

How are nature/form/dose of the antigen involved in oral tolerance induction?

Answer 5

Protein > Carbs > Lipids, Soluble = tolerogenic, particulate = nontolerogenic, low dose = regulatory t cells, high dose = anergy/deletion

Question 6

Do neonates tolerize?

Answer 6

No.

Question 7

How is the immune system hyporesponsive in the gut? Why?

Answer 7

Macrophages and DC’s have fewer TLR’s, Lymphocytes are difficult to activate and undergo apoptosis quickly. So it won’t respond to commensal bacteria.

Question 8

What do T regs do in the gut to decrease lymphocyte response?

Answer 8

Secrete IL-10 and TGFß.

Question 9

How is IgA secreted into the lumen?

Answer 9

Packaged and released through the IEC, binds to viruses and bacteria, prevents their adhesion to epithelium.

Question 10

Three ways antigens are taken up in the gut?

Answer 10

Direct sampling via dendritic cells, which extend a process between IEC’s to lumen. Movement into Peyer’s Patches via M cells. Movement through/ in between IECs for contact with macrophages and T cells.

Question 11

Which organisms do M cells almost exclusively transport?

Answer 11

Viruses

Question 12

Peyer’s Patches

Answer 12

Have circulating T cells and large follicular zone with B cells. Generate antigen responding cells which move through mesenteric lymph nodes to circulation, then back into lamina propria.

Question 13

Pathway from GALT to MALT

Answer 13

Gut associated lymphoid tissue to MLN, cells move through thoracic duct to heart, then back to MALT.

Question 14

Th1

Answer 14

Induced by IL-12, produce IL-2 and IFNgamma. Cause granulomas.

Question 15

Th2

Answer 15

Induced by IL-4, produce IL-4. Cause hypersensitivity

Question 16

Th17

Answer 16

Induced by TGFß and IL-6, produce IL-17 and 22, which release antimicrobial substances from IEC’s.

Question 17

Treg

Answer 17

Induced by TGFß. Cause tolerance

Question 18

Crohn’s Disease Histological Hallmark

Answer 18

Granulomas

Question 19

UC Histological Hallmark

Answer 19

Loss of surface cells to create pseudopolyps.

Question 20

Celiac Disease

Answer 20

Immune response to gluten (IL-15 by IEC and IFN gamma by T cells). Villi will flatten due to crypt hyperplasia. Causes malabsorption.

Question 21

Two types of allergic responses

Answer 21

IgE mediated (anaphylaxis, urticaria, asthma, rhinitis), Cell-mediated (gastrointestinal reactions like enterocolitis, enteropathy, celiac)

Question 22

Enterocolitis symptoms and mechanism

Answer 22

Early onset (birth-9mo), vomiting, bloody stool, diarrhea. Caused by milk, soy, rice, oats. Caused by reduced TGF-beta receptors and increased TNF alpha expression.

Question 23

Allergic Eosinophilic Esophagitis

Answer 23

Falls between IgE and Non-IgE mediated. Furrows in esophagus, rings, white plaques of eosinophils.

Question 24

Hygiene Hypothesis

Answer 24

Kids aren’t getting exposed to antigens, so they develop allergies.