EXAM #1: IMMUNOLOGY OF THE GI TRACT Flashcards Preview

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Flashcards in EXAM #1: IMMUNOLOGY OF THE GI TRACT Deck (48)
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1
Q
What is the big difference between mucosal immunity and "normal" immunity?
A
*Length of time*

-->Mucosal immunity does NOT last very long
2
Q
How long do mucosal antibody responses last?
A
Months to a year

(vs. serum antibodies that persist for decades/life)
3
Q
What are effector cells?
A
Lymphocytes that are "primed" to preform function immediately on contact with antigen
4
Q
What is tertiary lymphoid tissue?
A
Any place in the body that becomes infected by microorganisms
5
Q
What kind of lympoid tissue is the gut considered?
A
Tertiary
6
Q
What are the physical mechanisms that prevent infection of the GI tract?
A
1) Acidity of stomach
2) Peristoltic motility
3) Detergent action of bile
4) Mucus secretion
7
Q
What is GALT?
A
Gut Associated Lymphoid Tissue
8
Q
List the sites of GALT.
A
1) Peyer's patches
2) Appendix
3) Lymphoid aggregates in appendix/ large intestine
4) Lymphoid cells in lamina propria
9
Q
What is a Peyer's Patch?
A
Aggregates of lymphoid tissue found in the ileum of the small intestine
10
Q
What types of immunity are generated by Peyer's Patches?
A
1) IgA antibodies
2) CTL
11
Q
Describe the structure of a Peyer's Patch.
A
- M-cells within the membrane of microfolds
- B-cell rich follicle
- T-cell area
- Germinal center
12
Q
Where are APCs located in the Peyer's Patch?
A
T-cell rich areas adjacent to the Germinal Center
13
Q
What is the function of M-cells in Peyer's Patches?
A
1) Uptake of antigen by endocyotsis and phagocytosis
2) Presentation of antigen to APCs

****Note that M-cells are sites of infection*****
14
Q
List the microorganisms that utilize M-cells for introduction into the body?
A
1) Shigella--gets in via M-cells and then uses actin rockets to infect
2) Salmonella
3) Yersinia
4) Listeria
15
Q
What are IELs?
A
Intraepithelial Lymphocytes i.e. between enterocytes in the epithelium
16
Q
What type of lymphocytes are most IELs? What are the two subtypes of these cells?
A
T-cells
1) Alpha-Beta subtype*
2) Gamma-delta

*Classic T-cell
17
Q
What is the function of CD8+ IEL cells?
A
Cell-mediated immunity against:
1) Viral antigens
2) Intracellular bacterial antigens
18
Q
Where are CD4+ T-cells located in the gut wall?
A
Lamina Propria

vs. CD8+ T-cells in the epithelium
19
Q
In addition to CD4+ T-cells, what other immune cells are in the lamina propria?
A
- B-lymphocytes
- Plasma cells
- Macrophages
- Dendritic cells
- Eosinophils
- Mast cells
20
Q
Describe the basic immune response in the gut that results in IgA production.
A
1) M-cells uptake antigen
2) APCs bind antigen
3) APCs stimulate T-helper cells
4) T-helper cells stimulate antigen specific B-cells
21
Q
Once B-cells have been stimulated, outline the path that the cell will take to find the Lamina Propria.
A
1) Pre-plasma cells leave Peyer Patch via efferent lymphatic capillaries
2) Migrates via mesenteric lymph channels
3) Enter bloodstream via the thoracic duct
4) Go "home" to the Lamina Propria
22
Q
What is the role of addressins in B-cell stimulation?
A
These are the "homing" mechanisms that tell B-cells to go back to the Lamina Propria
23
Q
How do IgA secreting Plasma Cells get from the Lamina Propria to the gut lumen?
A
1) IgA binds "poly-immunoglobulin receptors" on basolateral side of enterocyte
2) Endocytosis and transport to apical side
3) Release of IgA dimer + secretory component
24
Q
What is "secretory component?"
A
Part of the poly Ig receptor that facilitates endocytosis of the IgA secreting plasma cell
25
Q
What is the function of secretory component?
A
Prevents the breakdown of IgA in the gut lumen by proteolytic enzymes
26
Q
What is the major immunoglobulin in secretions?
A
IgA
27
Q
What are the two subclasses of IgA?
A
IgA1=
- cleaved by bacterial IgA protease
- can fix complement via alternate pathway

IgA2= not susceptible to IgA protease
28
Q
What is the difference between the structure of IgA in the serum vs. mucousal sites?
A
Mucosal= IgA dimer

Serum= monomer
29
Q
What is the role of IgA in immunity?
A
1) Opsonization of small pathogens for phagocytosis
2) Anti-parasite immunity by facilitating eosinophil degranulation
30
Q
What is the role of gamma-delta T-cells?
A
1) Respond to NON-PEPTIDE antigen
2) Don't recognize normal MHC

****Quick immune response to pathogens that we are routinely exposed to without having to go through the entire process of normal T-cells*****
31
Q
What is the importance of mast cells in gut immunity?
A
1) Play a role in IgE-mediated immunity against parasites
2) Elicit food-induced allergic reactions
32
Q
What is oral tolerance?
A
Prevention of an immune response to the food you eat
33
Q
What is high dose tolerance?
A
Clonal deletion of antigen specific lymphocytes
34
Q
What is low dose oral tolerance?
A
Clonal anergy and T-reg suppression of the immune response
35
Q
What is the most common immunodeficiency?
A
Selective IgA deficiency
36
Q
What is the clinical presentation of Selective IgA deficiency?
A
Most are Asymptomatic but have a higher risk for Autoimmune disease

****Remember the A's*****
37
Q
What compensates for the absence of IgA in Selective IgA Deficiency?
A
IgM
38
Q
What class of antibody mediates Food Hypersensitivity?
A
IgE
39
Q
In Gluten-Sensitive Enteropathy, what protein is the immune response directed against?
A
Gliadin
40
Q
In what disease is there an increase in gamma-delta T-cells?
A
Gluten-Sensitive Enteropathy
41
Q
What is the treatment for Gluten-Sensitive Enteropathy?
A
Lifelong gluten-free diet
42
Q
What diseases are patients with Gluten-Sensitive Enteropathy at risk for?
A
1) GI Lymphoma
2) GI Carcinoma
43
Q
What is the pathologic feature of Ulcerative Colitis?
A
Inflammation of the large bowel
44
Q
What is the definitive treatment for Ulcerative Colitits?
A
Total Colectomy
45
Q
What is the pathologic feature of Chron's Disease?
A
Inflammatory AND granulomatous lesions of the terminal ileum and ascending colon
46
Q
What drug can be used to treat Chron's Disease?
A
Infliximab-- anti-TNF-alpha monoclonal antibody
47
Q
What disease is characterized by granulocyte inflammatory cells? Which is characterized by granulomatous lesions?
A
Granulocyte inflammatory cells= UC

Granulomatous lesions= CD
48
Q
What is the most common cause of Pernicious Anemia?
A
Autoimmune antibodies against IF or gastric parietal cells