Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Immunology Exam Two > Tolerance Induction/MHC Restriction > Flashcards

Tolerance Induction/MHC Restriction Flashcards

1
Q

Are HEVs present in the thymus?

A

No

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

What two organs lack afferent lymphatics?

A

Spleen and thymus

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

What hormones are produced by the thymus?

A

Thymulin, thymosin alpha-1, thymopoietin

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

Thymulin produced by the thymus is dependent on what mineral?

A

Zinc

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

What happened when the thymus was removed from neonatal mice?

A

Degeneration of the anterior pituitary within 30 days

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

What is the function of thymulin that is produced by the thymus?

A

Involved with T cell maturation and differentiation (can also affect the neuroendocrine system

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

In what organ do T cells mature?

A

Thymus

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

What does it mean when T cells become mature?

A

Learn tolerance of self aka “central tolerance induction”

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

What does it mean when a T cell is “nude”?

A

Doesn’t express CD4, CD8, or TCR

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

Nude T cells enter the thymus from what location?

A

Bone marrow

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

Where in the thymus do nude T cells proliferate?

A

Cortex

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

Nude T cells are resistant to what process?

A

Apoptosis

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

Why are nude T cells resistant to apoptosis?

A

They express little or no Fas protein

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

What is expressed heavily on nude T cells that help protect them against apoptosis?

A

Bcl-2

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

What does it mean when a T cell becomes a double positive (DP) cell?

A

Possesses both CD4 and CD8 co-receptor molecules, lots of Fas protein on surface, and very little Bcl-2

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

What is the most common lymphocyte in the thymus (80%)?

A

Double positive (DP) cells

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

What two tests must a DP cell pass to avoid death?

A

MHC restriction

Tolerance to self

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is CD44?

A

Receptor for hyaluronic acid
Associated with thymocyte migration events
Considered a marker for T-cell activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is CD25?

A

Alpha chain of IL-2 receptor

Favors IL-2 thymocyte proliferation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which DP test is considered “positive selection”?

A

MHC restriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which DP test is considered “negative selection”?

A

Tolerance to self

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What occurs in the positive selection DP test?

A

T cell must only recognize peptides presented on MHCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What occurs in the negative selection DP test?

A

T cell must not recognize self peptides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

During which DP test does 95% of the maturing T cell deaths occur?

A

Positive selection (MHC restriction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What cells check to see that T cells have receptors (TCR) that recognize one of the "self MHC" molecules (both I and II) during positive selection?
Cortical epithelial cells (CEC)
26
Where does the MHC restriction (positive selection) DP test occur?
Cortex of thymus
27
What happens to a T cell that recognizes peptides not presented by MHC molecules during positive selection?
Eliminated by apoptosis
28
When is a T cell referred to as a single positive cell (SP)?
After positive selection when it chooses either CD4 or CD8
29
What cells give the negative selection test?
Thymic dendritic cells and medullary thymic epithelial cells
30
After becoming single positive cells, where do the T cells migrate?
Medulla (to begin negative selection)
31
From where are thymic dendritic cells derived?
Bone marrow
32
Medullary thymic epithelial cells are related to what kind of cells (but have a different function)?
Cortical thymic epithelial cells
33
What is the negative selection DP test?
Thymic dendritic cells check to see if T cells recognize any of the self peptides displayed by MHC molecules on the cell's surface
34
What is the goal of the negative selection DP test?
Eliminate T cells that recognize self peptides
35
Thymic dendritic cells only live about how long in the thymus?
1 week
36
Which test, positive or negative selection, prevents against auto immune disease?
Negative selection
37
Which cells express tissue specific proteins (antigens) that are unique to different tissues/organs in the body?
Medullary thymic epithelial cells
38
Which cells are responsible for cross presentation?
Medullary thymic epithelial cells
39
What cells are responsible for displaying self peptides on MHC molecules?
Thymic dendritic cells
40
Are intracellular proteins found on MHC I or MHC II?
MHC I (endogenous)
41
Do thymic dendritic cells sample the surrounding environment and present exogenous proteins on MHC I or MHC II?
MHC II
42
Medullary thymic epithelial cells engage in what process where they regularly enclose portions of their cytoplasm within a membrane?
Autophagy
43
When medullary thymic epithelial cells engage in autophagy, do they present protein samples on MHC I or MHC II molecules?
MHC II
44
What is the location for negative selection DP test?
Medulla
45
Do mature T cells recognize MHC-peptide complexes?
Yes
46
Self antigens are presented on which cells of the thymus during the negative selection test?
Thymic dendritic cells and medullary thymic epithelial cells
47
How long does the T cell maturation process take?
About 2 weeks
48
What is the pass rate of T cell maturation?
1/30
49
What happens to T cells that fail the maturation process?
Death by apoptosis and eaten up by macrophages
50
About how many double positive T cells begin a DP test each day?
60 million
51
What is the riddle of MHC restriction and tolerance induction?
How any T cells can possibly pass both the positive and negative selection
52
What is a rogue T cell?
One that got out but should have been killed
53
What is the issue with rogue T cells?
Likely to be self-reactive
54
How are natural regulatory T cells able to enter into secondary lymphoid organs?
Expression of a gene called Foxp3 enabling them to receive adhesion molecules that are used as "passports" for temporary travel
55
What do people who lack the Foxp3 protein end to die young of?
Autoimmune disease?
56
What is peripheral tolerance?
When a virgin T cell strays into abnormal tissues and encounters a rare self antigen that they weren't exposed to in the thymus
57
What is a cell called when it recognizes its "cognate antigen" but does not receive the co-stimulatory signal?
Anergized
58
What happens to anergized cells?
They can't function and die quickly
59
What is the "two key" activation required of T cells?
1. Enough antigen to cluster receptors | 2. Co-stimulatory signals
60
What kind of cells present lots of antigen and co-stimulatory (B7) molecules?
Antigen-presenting cells
61
What is the extra level of protection against naive T cells that travel outside their normal traffic pattern?
Peripheral tolerance
62
When a T cell passes even through peripheral tolerance, what is the next layer of defense?
Tolerance due to activation-induced cell death (AICD)
63
What is tolerance due to activation-induced cell death (AICD)?
When stimulated many times by self antigens, T cells then become more sensitive to ligation of their Fas proteins thereby leading them to be killed via apoptosis
64
What is central tolerance?
Positive and negative selection tests
65
What is tolerance by ignorance?
Restricted traffic patterns preventing self reaction of T cells
66
What is the order of T cell tolerance?
``` Central tolerance Tolerance by ignorance Tolerance induction in secondary lymphoid organs Peripheral tolerance Tolerance due to AICD ```
67
Most B cells are tolerized where?
Bone marrow
68
After testing, B cells that do not react to self are sent where?
To circulate blood and lymph
69
What happens to virgin B cells that venture into tissues that meet their cognant antigen but do not receive T cell help?
Either anergized or deleted
70
What is the process by which B cells modify their receptors after they have been activated?
Somatic hypermutation
71
Can T cells go through somatic hypermutation?
No, only B cells
72
What cells are the source of antigen for B cells in germinal centers?
Follicular dendritic cells
73
Are self antigens usually opsonized?
No
74
Where does B cell tolerance occur?
Bone marrow
75
What is receptor editing of B cells?
When B cells that recognize "self" are given a chance to change
76
About what percent of B cells successfully go through receptor editing?
25%
77
What happens to B cells that get into tissues and deviate from their usual restricted travel?
Either anergized or deleted
78
Where are iTregs developed?
MALT
79
What is the function of iTregs?
Restrain the immune system to keep it from over-reacting to foreign antigen in tissue
80
How do iTregs work?
By producing cytokines that suppress the immune response
81
Where are nTregs developed?
Thymus
82
What is the function of nTregs?
To provide protection against T cells in lymph nodes with the potential to react against self antigens that escaped negative selection in the thymus
83
What type of "Treg" is thought to require direct cell to cell contact and are antigen specific?
nTreg
84
What type of "Treg" is mainly CD4+?
nTreg
85
What type of "Treg" can be either CD4+ or CD8+?
S.N. Tregs
86
Which is considered a strong interaction: positive or negative selection?
Negative selection
87
Which is considered a weak interaction: positive or negative selection?
Positive selection

Immunology Exam Two (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions