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IMMUNOLOGY > Lecture 24: Tolerance and Autoimmunity > Flashcards

Lecture 24: Tolerance and Autoimmunity Flashcards

1
Q

state of specific unresponsiveness to an antigen induced by prior exposure to that antigen

A

immune tolerance
tolerance is an active process

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2
Q

How does the immune system address inevitable reactivity to self

A

Elimination of self-reactive T cells in the thymus: Central tolerance

Failure to provide the signals to induce a T cell response: Peripheral tolerance

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3
Q

what is AIRE (autoimmune regulator)

A

transcription factor that facilitates expression of non-thymic proteins in the thymus to test reactivity

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4
Q

_____ anergy is initiated when T-cells are exposed to antigen in the absence of costimulation

A

Clonal

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5
Q

what is the mechanism of clonal anergy

A

suppression of NFKB and decreased production of cytokines (IL-2)

lasts for several weeks

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6
Q

what is immune paralysis

A

high doses of antigen that bypass APCs, bind TCR directly, lack costimulation and induce paralysis

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7
Q

antigen dose affects ____ of tolerance

A

induction

Very low doses of antigen fail to send a sufficient signal, inadequate co-stimulation occurs

very high doses can overstimulate the cells and initiate peripheral tolerance

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8
Q

where and when does central tolerance of B-cells occur

A

occurs in bone marrow once B-cell can express IgM (immature B cell)

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9
Q

random somatic mutations of B-cells occur in __________ organs, and must be controlled peripherally

A

secondary lymphoid

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10
Q

what things cause mature B cells to undergo peripheral tolerance

A

chronic antigen recognition
absence of costimulation
excessive suppressor cell activity
excessive T-independent antigen

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11
Q

once an antigen is eliminated, tolerance….

A

subsides

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12
Q

bone marrow activity (production of new cells) ______tolerance

A

reduces

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13
Q

immunosuppressive drugs _______ tolerance

A

prolong

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14
Q

______drive the immune response, _______turn it off

A

antigens, antibodies

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15
Q

antibodies have a feedback loop on _____cells to ______further production of antibodies

A

Bcells, inhibit

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16
Q

______antibodies inhibit antibody production in the newborn

A

maternal

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17
Q

Adaptive immune responses are _______Driven

A

antigen

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18
Q

adaptive immune response is initiated only when…? when does it cease?

A

initiated only on exposure to antigen
ceases when antigen eliminated

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19
Q

what happens when self or other antigens don’t reach lymphoid tissue

A

fail to induce immunity to tolerance
self antigens form immune privledged sites

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20
Q

the effect of antigen can be modulated by…?

A

adjuvants

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21
Q

antibodies suppress _____cell responses

A

B

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22
Q

IgM suppresses only..?

A

IgM

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23
Q

IgG suppresses production of _____ and _____

A

IgM and IgG

24
Q

Antibody mechanism of B-cell suppression?

A

inhibitory B-cell receptor CD32b

25
Q

abnormally high Ab concentrations (myeloma) inhibit….

A

normal Ab synthesis
increased susceptibility to infection

26
Q

what is the action of FcRn (neonatal immunoglobulin receptor)

A

regulates serum half life of IgG and albumin

endothelium, muscle, hepatic sinusoids

27
Q

________receptors inactivate or eliminate pathways that are no longer needed, suppress the activity of the lymphocytes when their mission is completed

A

inhibitory

28
Q

what does CD32b do

A

negative feedback that suppresses B-cell activation
crosslinking of BCR and Ab bound to CD32 w/ antigen

29
Q

what is the function of Treg cells

A

homeostasis of peripheral immunity + tolerance
induce apoptosis in effector cells

30
Q

what immunosuppressive cytokines do Treg cells produce

A
  • IL-10
  • IL-35
  • TGF-B

suppression of Tcell and macrophage function

31
Q

Treg deficiency results in…?

A

multisystemic autoimmunity and massive inflammation

32
Q

what are the Treg cells in cattle

A

WC1.1, WC1.2, γ/δ and Tcells

33
Q

where do Treg cells originate from, where are they induced

A

Originate in thymus
induced in secondary lymphoid tissues (most important in intestine)

34
Q

what induces cell cycle arrest in effector Tcells

A

Galectin

35
Q

what does CTLA-4 do

A

induces apoptosis of effector T cells

36
Q

what are the 3 ways Treg cells suppress immune responses

A

direct contact
suppressive molecules
interference w/ antigen presentation

37
Q

what ILs activate M2

A

IL-4, IL-13

38
Q

effect of Indoleamine 2,3 dioxygenase

A

tryptophan depletion and cell cycle arrest

39
Q

stress is highly …..

A

immunosuppressive

40
Q

disease resulting from an attack by an individual’s immune system against its own tissues

A

autoimmune disease

41
Q

Up to what percentage of new B and T cell receptors can bind self antigens?

A

50%

42
Q

what is cental tolerance

A

elimination of self-reactive T cells in the thymus

43
Q

what is peripheral tolerance

A

Failure to provide the signals to induce a T cell response

44
Q

what does it mean for tissues to be immune privileged

A

Areas of the body where inflammatory immune response does not occur following exposure to an antigen, ex) the eyes

45
Q

Which type of cell does not remain tolerant as readily as the other, and will reactivate if tolerance is not maintained?

A

B-cell

46
Q

what is functional deletion

A

The cell is still in the body, but the cell is no longer functioning

47
Q

can self antigens can induce immunity or tolerance.

A

no

48
Q

what is FoxP3

A

Transcriptional repressor protein of regulatory T cells

49
Q

What 3 things must be present for an immature Th cell to become a Treg cell?

A

IL-2, TGF-B, Retinoic Acid

50
Q

Can suppress macrophages, Th1 cells, Th2 cells, dendritic cells, natural killer cells, and Th17 production

A

IL-10

51
Q

Regulates T-cell activation, macrophages, and B-cell function

A

TGF-B

52
Q

What is the classically activated regulatory macrophage known as?

A

M1

53
Q

What regulatory macrophage s activated by IL-4+IL-13 and induces tolerance, suppresses inflammation, and is responsible for tissue repair?

A

M2

54
Q

IL-22 is produced by..?…and involved in..?….

A

Produced by Th17, involved in tissue healing

55
Q

IL-17 is produced by_______,stimulates____________ and mobilizes________

A

Produced by Th17 cells, stimulates growth factors, Th cells, epithelial cells, macrophages. Also mobilizes neutrophils to promote inflammation.

IMMUNOLOGY (26 decks)

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