2.9 Flashcards

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1
Q

Lymphocyte receptors generated during T and B

cell development include many that recognize

A

self antigens

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2
Q

A healthy immune system is able to discriminate

between

A

self and nonself antigens

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3
Q

only mount full response to nonself antigens
failure to prevent a response to self antigens
results in —

A

autoimmunity

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4
Q

A healthy immune system is able to discriminate
— microbes
only mount full response to non-commensal
microbes

A

commensal from non-commensal

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5
Q

failure to prevent a response to commensal

microbes results in

A

chronic inflammation

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6
Q

Particular antigens will result in an

2

A

immunogenic response or a

tolerogenic response

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7
Q

Figure 9-1. Central tolerance to self antigens

A

apoptosis (deletion)
change in receptors (receptor editing; b cells only)
development of regulatory T lymphocytes (CD4+)

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8
Q

Figure 9-1. Peripheral tolerance to self antigens

A

anergy
apoptosis (deletion)
suppression

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9
Q

Principal mechanisms of central T lymphocyte tolerance (2)

A

negative selection: deletion (CD4+ and CD8+ T cells)

development of regulatory T cells (CD4+ T cells)

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10
Q

Principal mechanisms of peripheral T lymphocyte tolerance (4)

A
generation of effector and memory t cells 
functional unresponsiveness 
(1.	TCR	does	not	send	
activating	signal
2.	T	cell	engages	an	inhibitory	
receptor	(CTLA-4	or	PD-1))
block in activation
apoptosis
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11
Q

T cell anergy (2)

A
1.	TCR	does	not	send	activating	signal	
because	no	costimulator engagement
2.	T	cell	engages	an	inhibitory	receptor	
CTLA-4:	block	&	remove	B7	costimulator
from	APCs
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12
Q

PD-1:

A

inhibits signaling within cell

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13
Q

Suppression

A

Regulatory T cells develop in the thymus or peripheral tissues on recognition of self antigens and
suppress the activation of lymphocytes that also recognize these self antigens

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14
Q

Regulatory T cells suppress immune responses by: (3)

A
1.	Cytokine	signaling
inhibits	activation	of	target	cells
2.	CTLA-4	expression
remove	B7	from	APCs
3.High	amount	of	IL-2	receptor
depletes	IL-2	in	local	area
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15
Q

regulatory t cells (2)

A

inhibition of t cell responses

inhibition of other cells

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16
Q
---	mechanisms	
activated	by	costimulators (e.g.	B7)	
and	cytokines	from	APCs	during	a	
response	to	foreign	antigens	(vs.	
self	antigens)
A

Anti-apoptotic

17
Q

Principal mechanisms of central B lymphocyte tolerance (3)

A

nonself reactive b cell
deletion
anergic b cell

18
Q

Principal mechanisms of peripheral B lymphocyte tolerance (3)

A

anergy
deletion
regulation byinhibitor receptors

19
Q

tissue injury:

A

autoimmune disease

20
Q

Figure 9-13. Mechanisms by which microbes may promote autoimmunity (3)

A

self tolerance: anergy or deletion
induction of costimulators on APCs: autoimmunity
molecular mimicry: autoimmunity