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Immunobiology > exam 3 > Flashcards

exam 3 Flashcards

1
Q

mucosal tissues

A

include components of the GI tract, respiratory tract, and urogenital tract; lined with epithelial cells that secrete mucin (major protein in mucus)

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2
Q

mucin

A

major protein in mucus; exists in membrane or soluble form; carbohydrates and cysteine residues create cross-linked thick gel

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3
Q

lamina propria

A

layer below epithelial cell layer

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4
Q

Describe the role of the epithelium in mucosal immunity

A

Epithelial barrier has tight junctions, adheren junctions, and desmosomes; tightly joined cells block pathogens from entering

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5
Q

MALT

A

mucosa-associated lymphoid tissues!! they contain specialized cells and structures that enable pathogen delivery to lymphoid tissue and activation of an adaptive immune response

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6
Q

Peyer’s patches

A

where lymphocytes are activated

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7
Q

M cells

A

don’t have follicles; responsible for delivering antigen to Peyer’s patches

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8
Q

Intraepithelial lymphocytes

A

protect the epithelial layer from intracellular infection

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9
Q

Isolated lymphoid follicles

A

where B cells are activated to produce plasma cells

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10
Q

Immune cells in healthy mucosal tissue include

A
  • activated T cells
    -intraepithelial lymphocytes
    -plasma cells
    -macrophages
    -DCs
    -innate lymphoid cells
    -mast cells
  • eosinophils
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11
Q
A
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11
Q

Invasive bacteria trigger production of these three cytokines from intraepithelial cells

A

IL-1, IL-6, TNF

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12
Q

viruses induce production of these cytokines

A

Type I interferon

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13
Q

Resident gut macrophages make

A

IL-10

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14
Q

Gut has a high basal level of active ____ leading to ___ and _____

A

TGFB; Tregs and IgA

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15
Q

invasive bacteria and viruses can induce ____ and _____ from dendritic cells, leading to _____ and ______ responses

A

IL-6 and IL-12; Th1 and Th17

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16
Q

Worms damage epithelia and induce these three cytokines

A

IL25, IL-33, TSLP

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17
Q

Worms damage epithelia and induce cytokines leading to activation of _____ and _____ responses

A

ILC2s and Th2

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18
Q

How do DCs capture antigen in the gut mucosa?

A

-uptake via goblet cells; apoptosis dependent transfer; non-specific transport

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19
Q

transcytosis of pathogens by M cells

A

this is the process by which M cells deliver pathogens to underlying lymphoid tissue; pathogens on phagocytosed by M cells on the luminal side and transported via vesicles toward the basal side. Some of the pathogen is delivered intact and the other is digested via phagolysosome. B cells on the basal side bind to antigen via receptor for antigen processing and presentation. Dendritic cells process pathogen and antigens for presentation to nearby T cells

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20
Q

Sampling of lumen antigens by DCs

A

DCs extend dendrites bewteen epithelial cells of mucous membranes ot capture antigen on the lumnial side for processing and presentation

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21
Q

Migration of lymphocytes in MALT

A

After induction, cells leave the PP and mesenteric lymph node and circulate. They re-enter using special receptors induced by mucosal DCs through retinoid production

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22
Q

Extravasation and migration of T cells to mucosal tissue

A

express L-selecting and a4:B7 (binds to endothelial receptor MAdCAm-1); right binding –> migrate out of bloodstream and into tissue; T cells destined to become intraepithelial cells swtich cell surface integrin to AE:B7 –. promoting binding to epithelial cell receptor E cadherin

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23
Q

IgA structure

A

exists as a dimer joined by J chain

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24
Q

soluble IgA transport at epithelial surfaces

A

SlgA binds to mucus

25
Q

Plasma cells within mucosal tissue secrete IgA and IgE isotypes, which

A

promote pathogen clearance and neutralization

26
Q

Protection of mucosal tissue against worm infection

A

Dendritic cells and mucosal epithelial cells drive detection of a helminth infection. Mucosal epithelial cells secrete IL-33 and (TSLP). These cytokines activate innate lymphoid cell 2 (ILC2) cells and three types of granulocytes found within the lamina propria: mast cells, basophils, and eosinophils. DCs activate naïve T cells to differentiate into TFH cells for B-cell activation and TH2 cells for mast-cell activation. Within the mucosal tissue, B cells switch isotype expression to IgE, which binds to the surface of granulocytes for antigen recognition. TH2 cells secrete the cytokines IL-3, IL-5, and IL-9 to recruit and activate granulocytes. TH2 cells also secrete IL-13 to repair damage to the epithelial cell layer. ILC2 cells secrete the cytokine IL-5 to activate basophils.

27
Q

IELs recognizing peptides from viruses/intracellualr

A

use CD8 a:B heterodimer; IEL releases perforin and granzyme or binding of Fas ligand

28
Q

IELs that have been stressed

A

express MIC-A, MIC-B to produce IL-15. Nearby cells are activated and They kill the epithelial cells by releasing perforin and granzyme; these carry CD8 a:a homodimer

29
Q

inducible protective mechanisms at mucosal sites

A

1) inflammation (immune response recruits monocytes, neutrophils, eosinophils to control infection) 2) IgA (transported across mucosal epithelium)

30
Q

constitutive mechansims at mucosal sites

A

1) mucus production by goblet cells 2) Paneth secretaion of anti-microbial peptides 3) low pH & lysozyme 4) microbiome - primes development of MALT; compete for nutrients and produce own anti-microbials

31
Q

immunoglobulin structure

A

2 heavy & 2 light chains; covalently linked by disulfide bonds; AG binding site between variable regions

32
Q

Fc region

A

constant regions (4 bottom) of heavy and light

33
Q

Fab

A

fragment antigen binding

34
Q

Variation in hypervariable loops/CDRs is important because

A

it allows for immunoglobulins with different CDRs to bind to unique antigens

35
Q

immunoglobulins can bind to macromolecules including

A

protein, carbohydrate, and nucleic acid

36
Q

Linear epitope

A

close in primary sequence (such as adjacent amino acids in the primary sequence of a protein). Linear epitopes are not destroyed if the three-dimensional structure of the antigen is destroyed, as long as the primary sequence is still intact.

37
Q

conformational epitope

A

dictated by the structure of the antigen. Conformational epitopes may or may not be driven by functional groups or atoms that are farther apart in the primary sequence, and they are always destroyed if the three-dimensional structure of the antigen is no longer intact

38
Q

What are the five immunoglobulin isotypes?

A

IgM, IgD, IgG, IgA, IgE

39
Q

IgG subclasses

A

IgG1-4; differ in hinge regions & these different classes exist because of class switch recombination

40
Q

igM structure

A

assembles as a pentameric structure & associates with the J chain

41
Q

IgA structure

A

exists as a dimer and associates with J chain; secreted in saliva, teaers, gut, mucus

42
Q

IgM is made in response to

A

carbohydrate antigens

43
Q

Effector functions of Igs

A

1) neutralization 2) opsonization 3) complement activation 4) activation of innate immune cells

44
Q

IgM is involved in which effector functions

A

neutralization & complement activation

45
Q

IgA is involved in which effector functions

A

neutralization, opsonization, complement activation

46
Q

IgG is involved in which effector functions

A

ALL

47
Q

IgD is involved in which effector functions

A

activation of innate immune cells

48
Q

What does it mean for an antigen to be multivalent?

A

having multiple epitopes, each allowing the binding of a different immunoglobulin

49
Q

What does it mean for an antigen to have repeating epitopes?

A

allows binding of more than one immunoglobulin of the same type

50
Q

recombination in Ig happens with

A

heavy chain is subject to somatic recombination

51
Q

IgM production

A

determined by alternative splicing; includes Cu region

52
Q

IgD production

A

determined by alternative splicing; includes Cs region

53
Q

What determines whether membrane bound or soluble Ig is produced?

A

poly A early - transmembrane region is removed
Poly A later - incorporates transmembrane region

54
Q

How does class switch recombination work

A

Within activated B cells, transcription of different immunoglobulin heavy chain constant regions exposes the associated switch regions to cytosine deamination by AID. Repair mechanisms remove the uracil from the switch regions and create nicked DNA. Because of the sequence similarity among the switch regions and the breaks within the DNA, repair proteins facilitate recombination at the nicked switch regions. This results in recombination of the new constant region to a location for use during heavy chain transcription and removal of the intervening sequence in a manner similar to V(D)J recombination.

55
Q

AID

A

is expressed in activated B cells and catalyzes the deamination of cytosine and the formation of uracil in DNA

56
Q

deanimation of cytosine to uracil in DNA produces mutations

A

1) DNA rep 2) base excision repair 3) mismatch repair

57
Q

IFN-y intiaties isotope switch of

A

IG1, IG3

58
Q

IL-4 intitiates isotype swtich of

A

IG2, IGE

59
Q

IL-5 intitiates isotype swtich of

A

IgA

60
Q

TGF-B intitiates isotype swtich of

A

IgA, IgG4

61
Q
A

Immunobiology (4 decks)

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