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GI Week 5 > GI Immunology > Flashcards

GI Immunology Flashcards

1
Q

What parts of the immune system make up the central immune system?

A

blood cells, spleen, liver, lymph nodes

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2
Q

What parts of the immune system make up the surface/barrier portion of the immune system?

A

skin with it’s cornified epithelia and ducts of exocrine glands

mucosal barriers of the eye conjunctiva, respiratory tract, GI tract and GU tract

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3
Q

Which does the central immune shift towards: Th1 or Th2?

A

Th1

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4
Q

What is the most common Ig type on central immunity?

A

IgG

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5
Q

Which does the surface immune system shift towards: Th1 or Th2?

A

Th2

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6
Q

What is the most common Ig type in surface immunity/

A

IgA1 and IgA2

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7
Q

What is the primary site for antigen entry into the body?

A

the Gut-Associated Lymphoid Tissue (GALT)

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8
Q

What are the four layers of defense in the GI tract?

A
  1. intrapethelial barrier
  2. lamina propria
  3. peyer’s patches in ileum
  4. mesenteric lymph nodes
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9
Q

What will direct the “parking” of lymphocytes in the GI tract?

A

selectins and integrins

in the GI system, beta7 will be the particular integrin of importance - all mucosal lymphocytes express it

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10
Q

How do vitamins differentially direct lymphocyte migration?

A

Being in the sun increases the concentration of vitamin D in the dendritic cells, which then secrete cytokins to localize immune cells to the skin

Eating vitamin A will increase vitamin A concentration in dendritic cells which will then secrete chemokines to get lymphocytes to the gut

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11
Q

What will beta-7 integrin be attracted to on the mucosal surface?

A

E-cadherin

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12
Q

About how many lymphoid follicles are present in a payer’s patch?

A

between 5-500 aggregated lymphoid follicles

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13
Q

When during development will discrete B and T cell reigons appear in the peyer’s patches?

A

19 weeks

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14
Q

When will germinal centers appear in the peyers patches?

A

after birth

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15
Q

What is the max number of peyer’s patch we reach?

A

250 in the mid-teens

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16
Q

About how many isolated lymphoid follicles are theire in the gut?

A

about 30,000!

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17
Q

What are the 7 defense strategies of the GI tract?

A
  1. block entry into organism
  2. block entry into cell
  3. prohibit spreading
  4. direct killing
  5. kill host cell
  6. expulsion
  7. nutrient deprivation
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18
Q

What are some of the strategies the epithelium use as mechanical barriers to block entry into the organs?

A
  1. tight junctions
  2. trefoil factors for rapid repair of perforations
  3. apical surface of enterocyte forms a selective barrrier by having a dense coating of microbilli and a layer of filamentous brush border called the glycoclyx
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19
Q

How do the cilia help block entry into the organism? Mucins? Neutralizing antibodies?

A

the cilia will push the bacteria along for expulsion

the mucin will just glob the bacteriat ogether

neutralizing antibodies will also glob the bacteria together so the an’t enter the cells

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20
Q

What type of B cells will make the neutralizing antibodies?

A

B1

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21
Q

Are the natural neutralizing antibodies part of the innate or adaptive immune system?

A

innate! Which is an unusual nuance!

they’re constitutively expressed by the B1 cells

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22
Q

What anti-microbial peptide in particular will the paneth cells produce?

A

alpha defensins

also lysozyme and phospholipase A2

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23
Q

What do alpha defensins do?

A

they are amphipathic and the hydrphobic area will lie down along the bacterial membrane and pile up into a tube which then flips over and pops a hole in the bacterial membrane

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24
Q

What do the M cells do?

A

they will take up antigen from the gut lumen by enocytosis and then trancytose it to the lymphatic tissue to introduce it to the APCs

25
Q

What are some examples of bacteria that will enter the epithelial barrier via M cells?

A

Yersinia pseudotuberculosis
Yersinia enterocolitica
Salmonella typhimurium
Shigella flexneri

26
Q

What is the PAMP/PRR relationship he wants us to remember for the gut?

A

TLR4 with LPS activating NF-KB to induce inflammation with nausea, fever and aches

27
Q

What cells will promote barrier repair in the epithelium?

A

intrapeithleial lymphocytes - they secrete a keratinocyte growth factor

28
Q

The majority if intraepithleial lymphocyte will express what CD?

A

CD8

29
Q

What are the two types of TCR you’ll see on lymphocytes in the eptihelial barrier?

A

alpha-beta (which are thymus derived)

gamma-delta (which are not)

30
Q

What layer of the gut wall is a reservoir for 70-80% of total lymphocytes?

A

lamina propria

31
Q

The T cells in the lamina propria are predmoninantly what type?

A

CD4

32
Q

Which T cell branch will promote defense against intracellular pathogens?

A

Th1

33
Q

What are the main cytokines of the Th1 branch?

A

IFNgamma
TNA-alpha
IL-12

34
Q

What Th cell will forucs on defense against helminsh?

A

Th2

35
Q

What are the predominant cytokines of the Th2 response?

A

IL-10, IL-13, IL-5 and IL-4

36
Q

What Th cell is the oldest evolutionarily and probably the most important?

A

Th17 - extracellular bacteria and parasites

37
Q

What are the predominant cytokines of the Th17 cells?

A

IL-17
IL-21
IL-22

38
Q

What Th cells regulate tolerance?

A

Treg cells with IL-10

39
Q

Again, how do neutralizing antibodies (innate or adaptibe) block bacterial entry into the cell?

A

agglutinate them and sterically block their adherence to host cells, precliding invasion

40
Q

Does a B cell require antigen presentation to a T cell in order to become active?

A

No - that’s the more common route, but it’s possible for a DC cell to directly activate a B cell and cause it to class switch without going through antigen presentation to a T cell

41
Q

The B and T cells that are activated in the epithlium and lamina propria….where do they fully mature?

A

they get activated, but the nthey head to the lymph node for nourishment while they’re maturing and then they enter the circulation to get back to the region of infection

42
Q

What two aspects of the vascular reponse will inhibit spreading?

A

coagulation

vaso-constriction

43
Q

What interferon is important for prohibiting spread? How?

A

Interferon alpha and Interferon beta (type 1)

they will increase MHC class I expression and induce cell mediated cytotoxicity so the infected cells are killed and don’t get a chance to spread the infection

44
Q

Antiboyd produced in the germinal centers of the lamina propria is released directly into the intestinal lumen. Where ist he destination for antibody produced in the mesenteric lymph nodes?

A

open circulation

45
Q

What are some of the mediators of direct killing of bacteria in the GI tract?

A

antimicrobial peptides like alpha defensin

bacterial permeability increasing proteins
lysosomes and stomahc environment
complement
ROS
RNS
46
Q

What willl make beta-defensins?

A

leukocytes and epithelial cells

47
Q

What are some f the cells involved in killing infected host cells?

A

natural killer cells
natural killer T cells
cytotoxic T cells

48
Q

In general, what aspects of the GI tract promote expulsion of bacteria?

A
  1. vasoactive substances increase mucous production
  2. smooth muscle contraction
  3. cilia-mediated espulsion out the rectum
49
Q

What Ig is important for expulsion?

A

IgE

will trigger release of the vasoactive substances

50
Q

Where is the likely location for development of plasma cells that produce IgE antibodies specific to intestinal helminths?

A

lamina propria of the gut for activation and then mesenteric lymph nodes for mautration

51
Q

How do we deprive bacteria of iron?

A

lactoferrin removes it

52
Q

How do we deprive bacteria of manganese?

A

natural resistance-associated macrpahge proteins

53
Q

How do we remove zinc?

A

ZIP/ZnT families of transporters

54
Q

What broad spectrum scavenger of dibalent cations will sequester Ca, Fe, Zn and Mn from the bacteria?

A

calprotectin

55
Q

How do we sequester lipids from the bacteria?

A

lipid transport using a small serum protein called lipocalin

56
Q

How do we remove tryptophan form the bacteria?

A

indoleamine 2,3-dioxygenase

57
Q

Besides IL-10, what does te immune system use to shut down IL-1.

A

It can secrete free IL-1 receptor so it will just bind it up and not have an effect

58
Q

Gut pathology predominantly uses Th1. WHat’s the exception?

A

food allergies use Th2

also helminths

59
Q

What does salmonella use to get into a cell?

A

Type III secretion system causes ruffling of the membrane so the bacteria can bore it’s way in while the cytoskeleton just restructures around it

GI Week 5 (6 decks)

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