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Mercy CLS 1: Immunology > 11) Control mechanisms > Flashcards

11) Control mechanisms Flashcards

1
Q

major aspects of immune response that need regulation

A
  • development of pathways of immunocompetence
  • response of mature lymphs to Ag
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2
Q

draw the tolerance kinetics graph

A
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3
Q

tolerance

A

state of unresponsiveness to an epitope

Ag-specific

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4
Q

tolerance occurs when interaction with Ag + lymph results in….

A
  • inactivation
  • deletion
  • apoptosis
  • become anergic
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5
Q

anergic lymph

A

unresponsive

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6
Q

only cells with ——– can be tolerized

A

Ag-specific receptors

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7
Q

(t/f) tolerance can only be achieved at certain stages of development

A

false; any stage

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8
Q

how are immature lymphs tolerized?

which cells are tolerized?

A

negative selection

T-cells —thymus, when cells express TCR, 𝛼β, CD4 and CD8

B-cells —in BM

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9
Q

result if immature T and B cells are exposed to foreign antigen

A

inactivation
(not normal)

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10
Q

causes of autoimmune disease in relation to lymph development

A
  • self-reactive lymphs escape negative selection (just below critical affinity threshold)
  • self-antigens hidden during development
  • B-cell negative selection not as stringent as T-cell (not a problem because most Ag are T-dependent)
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11
Q

how can tolerance be induced in mature T-cells?

examples

A

presentation of Ag in incomplete or ineffective way

  • B7-CD28 interaction missing
  • Ag presented by pancreas, liver, kidney cells induced to express MHC II (no costimulatory signal)
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12
Q

anergized T-cells do not make…

A

IL-2

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13
Q

tolerance can reverse if induced by…

A

Ag presented by pancreas, liver, kidney cells induced to express MHC II (no costimulatory signal)

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14
Q

how can tolerance be induced in mature B-cells?

A

absence of T-cell signals

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15
Q

T-suppressors usually CD– +

A

4

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16
Q

possible mechanisms of T-suppressor action

A
  • produce inhibitory cytokines (IFN-𝛾, TGF-β)
  • CD8+ cells may have cytotoxic effects on other T-cells
17
Q

general factors that ↑ tolerance

A
  • fetus only response with IgM
  • elderly, general decrease in immune function
  • malnutrition
  • Bare lymphocyte syndrome
18
Q

how does malnutrition contribute to tolerance?

A
  • ↓ T-cells
  • impaired complement system
  • impaired phagocytosis
19
Q

no MHC expression on any cells
no T-cell response
B-cells produce only IgM

A

bare lymphocyte syndrome

20
Q

doses of Ag that induce tolerance vs immunity

A

low and high doses: tolerance
intermediate doses: immunity

21
Q

duration of tolerance is shorter in —– lymphs

A

B
(maintained 49 days, while T-cells live 100 days)

22
Q

why do T-cells need to last longer than B-cells?

A

thymus atrophies with age
BM replaces B-cells more rapidly

23
Q

reasons to induce tolerance

A
  • prevent transplant rejection
  • control autoimmune disorders
  • control allergic diseases
  • create drug therapies
24
Q

when does tolerance occur in both lymph lines?

A
  • T: within 24 hours of exposure
  • B: within 10-11 days of exposure
25
Q

how come immunologic/tolerance status of an individual reflects the T-cell population?

A

even if B-tolerance is gone, individual is still tolerant because most Ag are T-dependent

26
Q

Antigens that are sequestered in hidden spots that are only exposed with trauma

A
  • lens protein of eye
  • spermatozoal Ags
  • cartilage Ags
27
Q

(weak/strong) immunogens are rendered tolerant more easily

A

weak

28
Q

injection of Ag in —– form often results in tolerance

A

soluble, monomeric form

(less likely to be taken up by APCs)

29
Q

tolerance is easy to induce in newborns because…

A

low APC population

30
Q

destroying/blocking functions of ———— cells can result in tolerance

A

APC

31
Q

effect of metabolism of ag on tolerance

A

nonmetabolizable substances cannot be presented, and thus result in tolerance

32
Q

how can Ab regulate the immune response?

A
  • feedback inhibition; when Ag is bound by a lot of Ab, only the highest affinity Abs can bind to the remaining Ag
  • FCR regulation
33
Q

drugs/therapies used to suppress the immune system

A
  • cytotoxic agents (methotrexate)
  • corticosteroids
  • immunosuppressants (FK506, cyclosporine, rapamycin)
  • radiation
34
Q

how do cytotoxic agents work?

A

kill rapidly dividing cells, including lymphs

35
Q

how do immunosuppressants work?

A

prevent T-cell activation

36
Q

how does radiation work?

A

affects hematopoietic system

at proper dose, lymphs may be restored in weeks

Mercy CLS 1: Immunology (19 decks)

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