2.9

Question 1

Lymphocyte receptors generated during T and B

cell development include many that recognize

Answer 1

self antigens

Question 2

A healthy immune system is able to discriminate

between

Answer 2

self and nonself antigens

Question 3

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

Answer 3

autoimmunity

Question 4

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

Answer 4

commensal from non-commensal

Question 5

failure to prevent a response to commensal

microbes results in

Answer 5

chronic inflammation

Question 6

Particular antigens will result in an

2

Answer 6

immunogenic response or a

tolerogenic response

Question 7

Figure 9-1. Central tolerance to self antigens

Answer 7

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

Question 8

Figure 9-1. Peripheral tolerance to self antigens

Answer 8

anergy
apoptosis (deletion)
suppression

Question 9

Principal mechanisms of central T lymphocyte tolerance (2)

Answer 9

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

development of regulatory T cells (CD4+ T cells)

Question 10

Principal mechanisms of peripheral T lymphocyte tolerance (4)

Answer 10

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

Question 11

T cell anergy (2)

Answer 11

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

Question 12

PD-1:

Answer 12

inhibits signaling within cell

Question 13

Suppression

Answer 13

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

Question 14

Regulatory T cells suppress immune responses by: (3)

Answer 14

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

Question 15

regulatory t cells (2)

Answer 15

inhibition of t cell responses

inhibition of other cells

Question 16

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

Answer 16

Anti-apoptotic

Question 17

Principal mechanisms of central B lymphocyte tolerance (3)

Answer 17

nonself reactive b cell
deletion
anergic b cell

Question 18

Principal mechanisms of peripheral B lymphocyte tolerance (3)

Answer 18

anergy
deletion
regulation byinhibitor receptors

Question 19

tissue injury:

Answer 19

autoimmune disease

Question 20

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

Answer 20

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