4. Gut Immunology

Question 1

What is the largest immune organ in the body that consists of multi-follicular Peyer’s Patches and Isolated Lymphoid Tissue (ILT)

Answer 1

Gut-Associated Lymphoid Tissue (GALT)

Question 2

What are defensins

Answer 2

Diverse antimicrobial peptides (AMPs) contributing to the antimicrobial action and mucosal host defense in the GI

Question 3

What immunoglobulin is key for maintaining a Peaceful Bacteria-Host interaction

Answer 3

Secretory IgA

• does not activate complement
• does not activate phagocytes
• resistant to proteolysis

Question 4

What is Dysbiosis

Answer 4

Bad relationship between gut microflora leading to DYSREGULATION of the immune system and inflammation

Question 5

What do Short-chain fatty acids do for our immune system

Answer 5

Promotre Treg differentiation and secretory IgA production and stimulate production of mucus

Question 6

What is food allergy and celiac disease

Answer 6

Failure to induce tolerance to food proteins

Question 7

Why is peripheral tolerance needed for GI

Answer 7

Intestinal antigens are not available in the thymus so Central Tolerance does not prevent responses against intestinal antigens such as food and commensal organisms

Question 8

What CD is required for oral tolerance

Answer 8

CD25+

Question 9

The most common forms of immune-mediated adverse reactions to food (Type 1 hypersensitivity) are characterized by

Answer 9

Development of IgE against the food allergens

Question 10

What types of hypersensitivity are associated with food allergies

Answer 10

Type 1- IgE mediated

Types 3 and 4- Non IgE mediated

Question 11

Describe the primary allergen encounter

Answer 11

• Ingested allergen elicits an adaptive immune response
• B cells mature into plasma cells to make IgE to allergen
• IgE enters circulation and is bound by FcRE (CD23)** on mast cells in the tissues

Question 12

Describe the secondary allergen encounter

Answer 12

Cross-linking of allergen causes mast cell degranulation that releases vasoactive amines, cytokines/chemokines and lipids

Question 13

Why do GI allergens (food) cause allergic responses in skin

Answer 13

After primary encounter allergen fragments are internalized from the distributed throughout the body

Question 14

What are some mediators of Mast Cells

Answer 14

Histamine
TNF-a and IL-1
Prostaglandins
IL-5
Leukotrienes

Question 15

What cells are central for both local and systemic manifestations of food allergy

Answer 15

Mast cells

Question 16

GI manifestations of food allergy are dependent on what ILs

Answer 16

IL-4
IL-13
IL-9

Question 17

How do Treg cells control food allergy

Answer 17

Treg cell derived IL-10 and TGF-B suppress Th2 immunity and INHIBIT MAST CELL reactivity, REDUCE IgE synthesis and may increase IgG and IgA synthesis

Question 18

What supplements suppress inflammation

Answer 18

Vitamin D, A and folate

Question 19

How does the GUT MICROBIOTA suppress allergic immune responses

Answer 19

Induction of Treg cells and or direct suppresion of Basophils and MAST CELLS

Question 20

Skin prick allergen testing using what type of hypersensitivity

Answer 20

Type 1

Question 21

How do peanuts and other nuts contribute to shock

Answer 21

Production of C3a

Question 22

What plays the central role in food-induced anaphylaxis

Answer 22

Mast cells activated by IgE cross-linking of FceRI

Question 23

What allergens are associated with wheat

Answer 23

Alpha-amylase inhibitors
Agglutinin
Peroxidase

Question 24

What is Food-Dependent Exercise-Induced Anaphylaxis (FDEIA)

Answer 24

Exercise or aspirin enhance absorption of undigested immuno-reactive allergens into circulation

Question 25

What is an example of Non-IgE mediated food allergy

Answer 25

Cow’s milk allergy where symptoms don’t show for over 48 hours
is NOT lactose intolerance
Breastfeeding mother should remove milk from diet also

Question 26

What are the genetics behind Celiac Disease

Answer 26

HLA-DQ2 and DQ8 play a role in orchestrating adaptive immune response against gluten peptides

TG2 are associated with the disease (tissue transglutaminase 2)

Question 27

CD patients express what HLA

Answer 27

HLADQ2.5

Question 28

What type of hypersensitivity is associated with CD

Answer 28

Type 4