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Gastrointestinal > Immunity of the GI tract > Flashcards

Immunity of the GI tract Flashcards

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1
Q

True or false: the GI mucosal surface is colonized by bacteria

A

True

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2
Q

What is the most abundant isotype of Ig in the body?

A

IgA

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3
Q

What is the difference between the mucosal antibody response vs serum antibody response?

A

Memory is much shorter –month to years as opposed to decades

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4
Q

What is the response of lymphocytes that reside within the epithelium and lamina propria of the intestinal mucosa?

A

No immune induction

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5
Q

What are the two primary lymphoid tissues?

A

Thymus

Bone marrow

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6
Q

What are secondary lymphoid tissue?

A

LN

Spleen

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7
Q

What are tertiary lymphoid tissue?

A

Any place in the body that becomes infected

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8
Q

True or false: you can get both T and B cell response in the gut mucosa

A

True

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9
Q

Where in the gut do most bacteria reside?

A

Colon + ileum

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10
Q

What is GALT? What parts of the GI tract are included in this?

A

Gut associated lymphoid tissues

Peyer’s patches
Appendix
Lymphoid aggregates

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11
Q

What is the histological makeup of GALT sites?

A

Distinct B cell follicles and T cell areas

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12
Q

What layer of the GI tract houses the lamina propria? What is this area’s importance?

A

Lamina propria

Promoting IgA and CTL responses

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13
Q

What are M cells in the GI tract?

A

Microfold cells in Peyer’s patches that constantly sample antigens from their environment

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14
Q

Where are APCs housed in the GI tract mucosa?

A

T cell areas

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15
Q

True or false: M cells do not physically interact with underlying APCs, to stimulate them

A

False–the do physically stimulate them

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16
Q

What are the bacteria that can bind to the M cells in Peyer’s patches and gain entry into the cell?

A

Salmonella
Yersinia
Listeria
Shigella

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17
Q

What are the two mechanisms of bacterial uptake via M cells?

A

Phagocytosis and macropinocytosis

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18
Q

What happens when Shigella enters the M cells?

A

Busts out of the vesicle it was contained in, and shoots around into neighboring cells

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19
Q

What are intraepithelial lymphocytes?

A

Primarily T lymphocytes that are embedded in the GI epithelium, and are waiting for the same antigen to come back and kill it (they’re already primed)

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20
Q

What are alpha-beta T cells?

A

Standard T cells

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21
Q

What is the role of the mast cells in lamina propria?

A

Allow for hypersensitivity reactions and reactions against parasites (IgE mediated)

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22
Q

What is the role of Th cells?

A

Get the info from the APCs and stimulate antigen specific B cells to form germinal centers

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23
Q

What happens to the pre plasma cells when they leave the Peyer’s patch through efferent lymphatic channels?

A

Migrate via mesenteric lymph channels to the bloodstream via the thoracic duct to go home to the lamina propria

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24
Q

What are the proteins that play a role in the homing mechanism for pre plasma cells that are stimulated in the GI tract?

25
Where are fully matured plasma cells located in the GI tract (which layer)? What antibody do they secrete?
Lamina propria | IgA
26
What is the receptor that binds IgA that plasma cells produce to translocate it through the epithelial cells?
Poly-Ig-receptor
27
What is the role of the secretory component of the poly-Ig receptor that is broken off when IgA translocates through the epithelial cell?
Prevent degradation of IgA via the proteolytic enzymes that are in abundance in the gut
28
What are the two differentiating characteristics of IgA?
Dimer (in mucosal form) | Can cross mucosal membranes
29
What are the two subclasses of IgA? What is the major difference between them?
IgA1 and IgA2. IgA1 can be cleaved by bacterial IgA1 protease, and fix complement (IgA2 cannot)
30
In what form does IgA exist in the serum?
Monomer (not a dimer as it is found in mucus, saliva, etc)
31
What is the MOA of IgA?
Opsonizes small pathogens for phagocytosis Prevents binding of microbes to epithelium
32
Eosinophilic degranulation occurs when it binds what part of the IgA antibody? What is this important for?
Fc-alpha-R Parasitic immunity
33
What are gamma/delta T cells?
Serve as antigen-nonspecific initial line of defense Can respond to non-protein antigens
34
What is difference between plasma cell migration from Peyer's patches compared to T cells?
Same basic process
35
What is the role of IL-8?
Inflammatory cytokine that upregulates the expression of cell adhesion molecules on epithelial cells + chemoattractant for PMNs
36
What is the role of ICAM-1 on intestinal epithelial cells?
Binds PMNs to allow for extravasation
37
What is the role of LFA-3?
Binds PMNs to allow for extravasation
38
What is the role of E-selectin?
Binds PMNs to allow for extravasation
39
What is the role of P-selectin? Where is this stored? What activates its release?
binds to PMNs to allow for extravasation Stored in Weibel-palade bodies TNF-alpha
40
What are Weibel-palade bodies?
Vesicles found in endothelial cells that store vWF and P-selectin
41
What cells secrete IL-1? Function?
Macrophages, monocytes and fibroblasts, Increase adherence protein expression
42
What cells secrete TNF-alpha? Function?
Inflammatory cytokine that is secreted by macrophages, CD4+ lymphocytes, and granulocytes Pyrogen and acute phase protein
43
What is oral tolerance?
The immune system does not respond to certain GI antigens since they may be needed for nutrition
44
What is the MOA of high dose oral tolerance?
High doses causes a clonal deletion of antigen-specific lymphocytes
45
What is the MOA of low dose oral tolerance?
Clonal anergy + regulatory T cells suppress immune responses
46
What is selective IgA deficiency? Why is this not very symptomatic?
Not able to make IgA, thus are predisposed to mucosal infection IgM can take on the role of IgA
47
What is the antibody that mediates hypersensitivity type I reactions?
IgE
48
What is the cause of Gluten intolerance?
Gliadin not broken down into amino acids
49
What is the molecule that binds to gliadin, and allows for it to bind to MHC molecules?
transglutaminase
50
What disease has an associated increase in gamma-delta cells?
Celiac disease
51
What is the problem with continuing to eat gluten despise having celiac disease?
Increases the incidence of GI lymphoma and carcinoma
52
What is ulcerative colitis?
Inflammation that is limited to the large bowel, causing ulcer formation and a loss of mucosal absorptive function
53
What is the treatment o refractory ulcerative colitis? Why is this a definitive cure?
Total colectomy | Disease does not affect the small intestie
54
What is Crohn's disease?
Inflammatory disease that can affect any portion of the GI tract, causing granulomatous lesions in the terminal ileum and ascending colon
55
What are the ssx of Crohn's disease?
Obstructive symptoms Abscess formation Fistulas
56
What is the treatment for Crohn's disease? MOA?
Infliximab-- anti TNF-alpha to reduce the inflammation
57
Why is surgery for Crohn's disease not a definitive treatment?
Disease tends to recur in unaffected areas of the bowel
58
What is the primary difference between UC and CD?
UC = granulocyte inflammatory cell activation and abscess formation CD = granulomatous lesions
59
What are the two MOA of pernicious anemia (not including dietary deficiency)?
Anti-intrinsic factor | Anti-parietal cells

Gastrointestinal (42 decks)

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