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Immunology > Module 5 > Flashcards

Module 5 Flashcards

1
Q

What are the six stages of B cell development?

A 
Repertoire assembly
Negative selection 
Positive selection
Searching for infection
Finding infection 
Attacking infection
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2
Q

What is the role of bone marrow strolls cells during early B cell development?

A

They regulate B cell development through the production of IL-7

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3
Q

What are the functions of the surrogate light chain?

A

Blocks further H-chain rearrangement
Signals proliferation
Signals light chain rearrangement

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4
Q

What is allelic exclusion?

A

A cell can only express one of its two gene copies

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5
Q

During B cell development what are the Ig gene recombination steps?

A

Pro B cell - H chain gene rearrangement
Pre B cell - L chain gene rearrangement
Immature B cell - rearrangement ceases

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6
Q

When is a developing B cell considered an immature B cell?

A

When it produces IgM surface receptors and releases from stromal cells into circulation

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7
Q

What Ig’s do immature B cells express?

A

IgD and IgM

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8
Q

What are anergic cells?

A

Nonfunctional B cells that reacted with soluble antigens in the bone marrow, but are released into circulation only to die after a few days.

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9
Q

What is the process of receptor editing?

A

The additional opportunities provided to self-reactive B cells to reorganize their light chains

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10
Q

What happens to developing B cells that despite reorganizing their lights chains are still self reactive?

A

Apoptosis

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11
Q

What is clonal deletion?

A

The death of self reactive developing B cells

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12
Q

What is the process of negative selection?

A

The elimination of self-reactive immature cells

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13
Q

What kinds of lymphocytes undergo negative selection?

A

B and T cells

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14
Q

What is central tolerance?

A

The immunological tolerance to self by B and T cells

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15
Q

What does peripheral tolerance do?

A

The peripheral tissues sometimes catch escaped self reactive B and T cells

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16
Q

What happens to naive B cells after the exit the bone marrow?

A

They head to the lymph nodes for positive selection by the FDC

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17
Q

What does FDC stand for?

A

Follicular dendritic cells, the structural stromal cells that interact with immature B cells and positively select for survival

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18
Q

Final two phases of B cell development depends on what?

A

An encounter with an antigen

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19
Q

What are the four steps that B cells go through in their final development phases in the lymph node?

A
  1. Mature naive B cell encounters Ag
  2. Activation via partnership with Th
  3. Migration to primary follicle
  4. Proliferation and differentiation in German centers
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20
Q

What are the four stages of B cell development that occurs in the bone marrow?

A
  1. Stem cell
  2. Pro B cell
  3. Pre B cell
  4. Immature B cell
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21
Q

What are the five stages of B cell development that occur in the secondary lymphoid organs and circulation?

A
  1. Immature B cell
  2. Mature naive B cell
  3. Antigen-activated B lymphoblast
  4. Antibody secreting plasma cell
  5. Memory cell
22
Q

When the immature B cells leave the bone marrow, which Igs do they have?

A

They start with IgM and IgD

23
Q

Once B cells are in circulation, how do they achieve higher IgM and low IgD?

A

Through alternative splicing to give delta and mi chains then they gain access to primary lymphoid follicle

24
Q

What do nature B cells with low IgM and high IgD do next?

A

Enter circulation and bind antigen in lymphoid tissue draining infection

25
Q

What three steps happen once B cells reach the antigen-activated B lymphoblast stage?

A
  1. Alternative splicing to secret Ig
  2. Isotype switching
  3. Somatic hypermutation
26
Q

What is the purpose of B cells that have matured to the antibody secreting plasma cell level?

A

Fights active infections

27
Q

What is the purpose of B cells that make it to the memory cell level?

A

Prep for a future infection

28
Q

What is a thymocyte?

A

The T cell precursors that reach the thymus

29
Q

Where is the thymus located?

A

Above the heart

30
Q

What is the organization of the thymus?

A

It is sectioned into two regions, the cortex which is on top and densely packed and the medulla which is below and less densely packed.

31
Q

Why do we become more dependent on our pool of mature B cells as we age?

A

The thymus shrinks with age

32
Q

Are there more alpha-beta T cells or gamma delta T cells?

A

90-95% alpha beta TCR

33
Q

Why are there four chances for TCR beta chain formation?

A

Because VDJ happens on the beta chain locus and each allele has two constant regions

34
Q

What does pre-TCR signaling do to developing T cells?

A

Blocks further beta rearrangement and induced proliferation and expression of CD4 and CD8

35
Q

What does pT alpha chain do for developing T cells?

A

Acts as a placeholder for TCR alpha chain much like the B cell surrogate chain

36
Q

What are the two checkpoints on T cell development?

A
  1. Rearrangement first on the beta chain otherwise apoptosis
  2. Rearrangement second of the alpha chain otherwise apoptosis
37
Q

What percentage of thymocytes do not pass the selection process?

A

98%

38
Q

What does T cell education refer to?

A

The processes of positive and negative selection that thymocytes undergo

39
Q

What does positive selection accomplish?

A

Ensures that only T cells with functional TCRs are capable of interacting with self MHC survive and determine their functional role

40
Q

T cells during positive selection express what on their surface?

A

CD4, CD8 and TCR

41
Q

How if the effector function determined during positive selection?

A

If T cell interacts with MHC class 1 then it keeps CD8 and if it interacts with MHC class 2 it is CD4

42
Q

What does the process of negative selection accomplish?

A

It results in clonal deletion of self reactive T cells

43
Q

How are self reactive T cells identified?

A

They bind to tightly to thymocytes APCs presenting self and results in apoptosis

44
Q

What does AIRE stand for?

A

Autoimmune regulatory

45
Q

What is AIRE?

A

A transcription factor expressed by thymic epithelial cells

46
Q

What is the function of AIRE?

A

Induced expression of hundreds of tissue specific proteins to present on MHC to developing T cells during education

47
Q

What are the three types of T cells?

A

CTL, Th and reg

48
Q

What is the difference between tT reg cells and T reg cells?

A

tT are reg cells matured in the thymus and T reg cells mature in the periphery was

49
Q

What do T reg cells do?

A

Suppress the action of autoreactive T cells and contributes to peripheral tolerance

50
Q

What are the four stages of T cell development?

A
  1. Proliferation and differentiation of double-positive thymocytes
  2. Positive selection (T cell education)
  3. Negative selection (T cell education)
  4. Entry to circulation

Immunology (11 decks)

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