Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SFM Exam 2 > Tolerance and Autoimmunity > Flashcards

Tolerance and Autoimmunity Flashcards

1
Q

What is immunological tolerance?

A

A specific unresponsiveness to an Ag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Autoimmunity results from what?

A

A breakdown in tolerance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where is central tolerance induced?

A

In immature self reactive lymphocytes in the primary lymphoid organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does central tolerance ensure?

A

That mature lymphocytes are not reactive to self Ags

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Immature lymphocytes specific for self Age may encounter these Ags in the generative (central) lymphoid organs and are either what?

A

Deleted by apoptosis, change BCR specificity (B cells only) or develop into Treg cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When is peripheral tolerance induced?

A

In mature self reactive lymphocytes in LNs or peripheral sites such as submucosal tissue and is needed to prevent the activation of these potentially dangerous lymphocyte clones in the periphery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What can happen to mature self reactive lymphocytes in the peripheral tissues?

A

Can be inactivated (anergy), deleted by apoptosis or suppressed by Treg cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which cytokine is a critical factor for survival and functional competence of Treg cells?

A

IL-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are induced Treg cells (iTregs)?

A

Mature Th0 cells outside the thymus that have acquired Treg phenotype and function (in LNs and GI tract)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Ag recognition by a naive Th cell in the presence of TGF-beta, IL-2 and RA induces what?

A

FOXP3 expression if IL-6 is not present resulting in the cell developing into a iTreg cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Ag recognition by a naive Th cell in the presence of TGF-beta and IL-6 prevents what?

A

FOXP3 expression leading to Th17 cell differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Retinoic acid, produced by DCs, facilities the generation of what?

A

Of FOXP3+ induced Treg cells from naive CD4+CD25- T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Natural Treg cells are generated by what?

A

Self ag recognition in the thymus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

All B cells with a BCR containing the lambda IgL chain undergo what?

A

BCR editing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which cell plays a key role in peripheral tolerance?

A

Tregs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to a T cell that recognizes an Ag without adequate CD80:CD28 costimulation?

A

Becomes anergic and incapable of responding to the Ag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the death receptor (extrinsic) pathway for apoptosis

A

T cell expressing death receptor Fas(CD95) binds to FasL on another cell which causes activation of the initiator caspase in the cell expressing Fas
Cell dies by apoptosis

18
Q

Describe the mitochondrial (intrinsic) pathway for apoptosis

A

Cytochrome c and other pro-apoptotic proteins leave the mitochondria and apoptosis pathway is triggered

19
Q

What role does AIRE play in the breakdown of central tolerance?

A

Mutations in AIRE protein cause a breakdown of central tolerance and are associated with decreased expression of peripheral tissue self Ags in the thymus
It has been proposed to function as a TF
In the absence of AIRE self reactive T cells are not eliminated and can enter tissues where the Ags continue to be produced and cause injury

20
Q

Which genes are associated with a breakdown in peripheral tolerance?

A

C4, CTLA4, Fas/FasL and FOXP3

21
Q

Describe the cell intrinsic function of CTLA4

A

Engagement of CTLA4 on a T cell may deliver inhibitory signals that terminate further activation of that cell

22
Q

Describe the cell extrinsic action of CTLA4

A

CLTA4 on Treg cells or responding T cells bind to B7 molecules on APCs to make it unavailable to CD28 and blocking T cell activation
Reduced B7 costimulation -> inhibition of T cell activation

23
Q

What is immunological ignorance?

A

T cells that are physically separated from heir specific Ags cannot become activated

24
Q

Which inhibitory cytokines are released by Treg cells?

A

IL-10 and TGF-beta

25
Q

What does immune privileged site refer to?

A

Observation that tissue grafts placed in certain anatomical sites can survive for extended periods of time

26
Q

Immune privileged sites include?

A

Eye, brain, pregnant uterus, ovary, testis, adrenal cortex and hair follicles

27
Q

What is the cause of all autoimmune diseases?

A

Failure of T or B cell self tolerance

28
Q

Which gene is strongly associated with autoimmune disorders?

A

MHC genes (mostly class II)

29
Q

What are the three different mechanisms by which microbial Ags can initiate an autoimmune disorder?

A

Molecular mimicry, polyclonal (bystander) activation, and release of previously sequestered Ags

30
Q

What is molecular mimicry?

A

Rheumatic fever is triggered by streptococcal infection and mediated by cross reactivity b/w streptococcal Ags and cardiac myosin
MS - T cells react with myelin basic protein and peptides from Epstein-Barr virus, influenza A and HPV

31
Q

What is polyclonal (bystander) effect?

A

Microbial infection resulting in a robust inflammatory response can cause a polyclonal activation of auto reactive lymphocytes in the cytokine field

32
Q

What is the mechanism of releasing previously sequestered Ags?

A

Microbes that kill cells and cause the release of sequestered Ags (DAMPs) lead to the development of autoimmunity

33
Q

What are the principal clinical manifestations of SLE?

A

Rash, arthritis and glomerulonephritis

34
Q

What is the most frequent Ab found in SLE?

A

Anti-DNA Abs which are responsible for glomerulonephritis, vasculitis and arthritis in these pts

35
Q

What is the principal diagnostic test for SLE?

A

Presence of anti-nuclear (DNA) Abs

36
Q

What is rheumatoid arthritis?

A

An inflammatory disease involving small and large joints associated with destruction of joint cartilage and bone

37
Q

What are the cells involved with RA?

A

Th1 cells, Th17, activated B cells, plasma cells and macrophages

38
Q

What is SLE mediated by?

A

Type III hypersensitivity reactions

39
Q

What is RA mediated by?

A

Type IV hypersensitivity reactions in which Th17 cells play a key role

40
Q

RA pts frequently have circulating what?

A

IgM or IgG called rheumatoid factor (RF) that react with the Fc portion of circulating IgG

41
Q

What is the diagnostic test for RA?

A

Presence of circulating rheumatoid factor

SFM Exam 2 (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions