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GI Final Exam > Gut Immunity, Nutrition, and adverse food reactions > Flashcards

Gut Immunity, Nutrition, and adverse food reactions Flashcards

1
Q

What is the most abundant Ig in the body?

A

IgA

-IgG would be the answer for blood

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2
Q

With an allergy which part of the immune system gets activated?

A

the adaptive part.

-the innate part always responds anyway

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3
Q

When we have a food allergy, what got knocked out?

A

oral tolerance

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4
Q

Which cells are important for oral tolerance?

A

iTreg cells

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5
Q

Describe the process of oral tolerance

A

We get the ag from with a dendritic cell, it goes to the mesenteric lymph node where it sees t cells and releases TGF-B, RA, and IDO to make Treg cells, they go to the epithelium and expand
-we always make plasma cells that secret a lot of IgA and that also goes back to the epithelium

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6
Q

Where are Ag’s captured in oral tolerance?

A

the lamina propria

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7
Q

What to DC’s use to induce IgA secreting plasma cells?

A

RA

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8
Q

How are gut-homing iTregs expanded in the lamina propria?

A

by IL-10 expressing macrophages

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9
Q

What do the iTregs do then?

A

they can suppress the systemic immune responses, including allergic sensitization, in an Ag-specific manner

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10
Q

What does Vit D, A, and folate do?

A

suppress inflammation

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11
Q

What does a high fat diet do?

A

promotes inflammation

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12
Q

How does the gut microbiota suppress allergic immune responses?

A

through the induction of Treg cells

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13
Q

What is involved with the effector mechanisms in allergies?

A

IgE and basophils and mast cells

-microbiota suppress basophils and mast cells

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14
Q

What specifically do iTregs suppress?

A

Th2 cells

-these are central to generating IgE and allergic effector cells

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15
Q

What is food allergy caused by?

A

Ag-specific immune response that occurs reproducibly on exposure to a given food

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16
Q

What are the two groups of immune reactions of food allergies?

A

IgE mediated and non

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17
Q

What are non-IgE mediated reactions mediated by?

A

T-cells (type 3 or 4 hypersensitivity)

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18
Q

after the first 3-5 years, what do most of us lose our sensitivity to?

A

milk, eggs, wheat, and soy

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19
Q

What allergies continue into adulthood?

A

peanuts, treenuts, fish, and shellfish allergies

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20
Q

What Th2 cytokines are GI manifestations of food allergy dependent on?

A

IL-4, 13, and 9

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21
Q

What is anaphylaxis?

A

a reaction resulting from sudden release of multiple chemical mediators as a result of events mediated by IgE Ab’s
-it affects a lot of things

22
Q

With the peanut allergy, what cytokines did the Th2 cell secrete to make B-cells make a bunch of IgE?

A

IL-4, 5, and 13

23
Q

What are mast cells activated by in the nut-mediated allergy?

A

IgE cross-linking the FceRI

-can also be mediated by IgG1-induced activation of Macs

24
Q

What increases the vascular permeability and smooth m. contractility in the anaphylaxis reaction?

A

PAF and histamine

-only PAF with the Mac situation

25
Q

What comes out when we increase the vascular permeability?

A

C3 and C5

26
Q

What cuts C3 and C5?

A

tryptase released from activated mast cells

-this exacerbates the cymptoms by activating even MORE mast cells

27
Q

What is Wheat allergy?

A

a classic food allergy

-IgE plays a central role

28
Q

What are the 6 causes of food interolance that we talked about?

A
  • absence of an enzyme (lactase?)
  • irritable bowel syndrom
  • food poisoning
  • sensitivity to food additives
  • recurring stress or psychological factors
  • celiac disease
29
Q

What is celiac disease?

A

chronic digestive condition is triggered by eating gluten

  • ppl with this are not at risk of anaphylaxis*
  • disease of digestive origin basical
30
Q

What is gluten?

A

a protein found in wheat and other grains

31
Q

What is CD caused by?

A

-it’s a systemic immune disorder caused by a permanent sensitivity to gluten

32
Q

What can CD be associated with?

A

GI findings… or anything really

33
Q

What antibody is the marker for CD?

A

anti-tTG2 ab’s

-95% of ppl who have CD go undiagnosed because they don’t have any symptoms

34
Q

Which 2 molecules are the main genetic predisposing factor for CD?

A

HLA-DQ2 and DQ8

-play a key role in orchestrating an adaptive immune response against gluten peptides

35
Q

What auto antibodies are found with this disease?

A

ab’s against the enzyme tissue transglutaminase 2 (TG2)

36
Q

Which cells phagocytose to get the Ag’s?

A

Macs

37
Q

Which cells endocytose to get the Ag’s?

A

DCs and B cells

38
Q

Are there any Ag-free MHC molecules on the APC?

A

no

39
Q

Why is gluten such a good antigen?

A

it has a lot of proline which is poorly digested in the small intestine due to lack of prolylendopeptidases

  • it also has a lot of glutamine
  • big chunks of it are left undigested
40
Q

What deaminates some of the glutamines on gluten?

A

TG2

  • transglutaminase 2
  • makes it charged…. not ours anymore! immune system recognizes it
41
Q

What heterodimer do APC’s have that binds the charged glutamine?

A

P6 of the HLA-DQ2.5

42
Q

What happens after the gluten is presented on those HLA’s?

A

self reactive T-cells are made and then type 4 hypersensitivity happens
-chronic inflammatory response as long as patients continue to ingest gluten

43
Q

What 2 ab’s are made when an APC presents the deamidated gluten peptide to the helper t cell?

A

Anti-gliadin ab’s and anti-TG2 antibodies

44
Q

Where do gluten peptides react with TG2?

A

in the subepithelial LAMINA PROPRIA

45
Q

How does the APC present the gluten peptides?

A

via HLA-DQ2 or DQ8

46
Q

What cytokines do the CD4 T cells secrete to induce the release of MMPs which ultimately results in mucosal remodeling and villus atrophy?

A

Th1 cytokines such as IFN gamma

47
Q

What cytokine links the adaptive immune system to the innate immune responses?

A

IL-15

48
Q

How do you test for CD?

A

-start with measuring IgA ab to human tissue transglutaminase (TTg)
-meausrement of total serum IgA can facilitate interpretation hen the tTG IgA is low
-

49
Q

What can be used to identify the unusual case of seronegative CD?

A

and intestinal biopsy

50
Q

What is recommended to confirm the diagnosis of CD in all cases?

A

and intestinal biopsy

51
Q

When can CD be excluded from our Dx?

A

if the individual lacks HLA DQ2 or 8 alleles

GI Final Exam (10 decks)

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