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Immunology > Lymphocyte Development (Exam 2) > Flashcards

Lymphocyte Development (Exam 2) Flashcards

1
Q

Where does lymphocyte rearrangement and maturation occur?

A

primary lymphoid organs

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2
Q

B cells rearrange and mature in the _________ and T cells in the _______.

A

bone marrow
thymus

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3
Q

What are the gene segments that randomly rearrange to form unique lymphocyte receptors?

A

V (variable)
D (diversity)
J (joining)
C (constant)

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4
Q

What two chains rearrange to form T cell receptors? B cells receptors?

A

T cell: beta + alpha chain
B cell: heavy + light chain

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5
Q

Match the order of chain rearrangement for T and B cells.

A

T cell: first beta, then alpha chain
B cell: first heavy, then light chain

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6
Q

What is different between the gene segment rearrangement in T cells between the beta chain and alpha chain?

A

beta chain: V, D, J, C segments
alpha chain: V, J, C (no D)

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7
Q

Which type of cell does its receptor rearrangement have extra attempts to make appropriate receptors before programmed for cell death if it is not selected for?

A

B cells

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8
Q

Which type of T cells are the first to develop?

A

gamma-delta T cells

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9
Q

What are the two main types of T cells?

A

gamma-delta
alpha-beta

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10
Q

Where are gamma-delta T cells located?

A

epithelial tissue

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11
Q

(T/F) Ruminants have more alpha-beta T cells than gamma-delta T cells.

A

False - opposite

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12
Q

(T/F) Gamma-delta T cells receptor gene rearrangement is not a random process unlike alpha-beta T cells.

A

True

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13
Q

Explain how gamma-delta T cells rearrangement occurs since it is not randomized.

A

created in “waves” where same receptors develop and go to a specific type of epithelial tissue

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14
Q

Fill in the missing step in alpha-beta cell development:

Stem cells –> ______ –> intermediate form for gene rearrangement.

A

Pro-T cells

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15
Q

During alpha-beta T cell development, the ______ chain is rearranged randomly and then binds to a ______ of the opposite chain.

A

beta
surrogate

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16
Q

What is the purpose of a surrogate chain in alpha-beta T cell development?

A

these proteins bind to take place of unrearranged chain

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17
Q

What is the purpose of a surrogate chain in alpha-beta T cell development?

A

these proteins bind to take place of the unrearranged alpha chain so beta chain can go to cell surface as a “checkpoint” before continuing

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18
Q

Once a full lymphocyte receptor with both chains is developed and rearranged, the cell must have __________ to become mature.

A

weak antigen recognition

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19
Q

What is meant by “checkpoints” in lymphocyte development?

A

“stop signs” at different steps which require a cell signal to prevent cell death and continue on in development

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20
Q

What is called when a cell is automatically programmed for death when it does not send an appropriate signal to survive?

A

death by neglect

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21
Q

In the first step of lymphocyte development from a “pro” to a “pre” cell, signaling molecules must be present in order to prevent cell death. Which signaling molecules are required by B and T cells?

A

B cells: coreceptors
T cells: CD3 (marker on cell surface)

22
Q

Coreceptors that prevent cell death in developing B cells are made up of _____ and _____ molecules.

A

Ig(alpha) + Ig(beta)

23
Q

Explain the difference between strong and weak antigen recognition. Which is selected for? Which will undergo cell death?

A

strong: lymphocyte receptor strongly recognizes self-antigen

weak: lymphocyte receptor weakly recognizes self-antigen

weak
strong

24
Q

Strong antigen recognition undergoes (positive/negative) selection and weak antigen recognition undergoes (positive/negative).

A

negative
positive

25
Q

What is meant by double-positive T cells? Single-positive?

A

double-positive: CD4 + CD8 put on developing cell so it can bind to either Class I or Class II MHC

single-positive: once MHC binds, CD8 or CD4 is downregulated depending on which it binds to

26
Q

What is failure of positive selection?

A

T cell fails to interact successfully with MHC after it has developed a receptor and it undergoes cell death

27
Q

Process of lymphocytes being positively selected, and therefore not deleted, in the primary lymphoid organ due to their ability for weak antigen recognition.

A

central tolerance

28
Q

Process of ensuring mature single-positive lymphocytes released into the circulation have weak antigen recognition.

A

peripheral tolerance

29
Q

How can you get both IgM and IgD antibodies co-expressed on the same cell?

A

VDJ rearrangement randomly couples with mu (u) or delta (d) constant regions

30
Q

What is the largest contribution to antigen receptor diversity?

A

junctional diversity

31
Q

What is junctional diversity?

A

removal or additional of nucleotides at junctions of V/D, D/J, or V/J segments at the time these segments are joined

promotes diversity of lymphocyte receptors

32
Q

Process of VDJ rearrangement that brings together multiple gene segments that combine randomly which produce different receptor.

A

combinatorial diversity

33
Q

What two types of nucleotides are added for junctional diversity?

A

P + N nucleotides

34
Q

Match each characteristic to either a P or N nucleotide:

  1. short lengths | up to 20
  2. added randomly | added to VDJ junctions
A

P: short lengths, added to VDJ
N: up to 20, added randomly

35
Q

What enzyme mediates the addition of new nucleotides to gene segments in lymphocyte development?

A

TdT enzyme

36
Q

Where are B-1 B cells from?

A

fetal liver

37
Q

B-1 B cells only express _____ antibody and _____ molecule.

A

IgM
CD5

38
Q

(T/F) A B-1 B cell needs to be stimulated to secrete antibody.

A

False - makes antibody naturally

39
Q

What is the function of IgM antibodies produced by B-1 B cells?

A

attack commensal bacteria that get across epithelial layer

40
Q

B-1 B cell receptors bind to ______ antigens with (high/low) affinity.

A

carbohydrate
low

41
Q

Marginal zone B cells are a type of ______ cell.

A

B-2 cell

42
Q

Where are marginal zone B cells located?

A

white pulp of spleen

43
Q

Function of marginal zone B cells

A

bloodborne antigen recognition

44
Q

What antibody or antibodies do marginal zone B cells express? What else do they express?

A

IgM
complement receptor

45
Q

What kind of antigens do marginal zone B cells recognize?

A

protein + carbohydrate antigens

46
Q

(T/F) Marginal zone B cells require T cell help to respond to antigen.

A

False - do not need help

47
Q

What are two types of B-2 B cells?

A
  1. follicular B cells
  2. marginal zone B cells
48
Q

Which antibody or antibodies do follicular B cells express?

A

IgM + IgD (co-expression)

49
Q

Where are follicular B cells located?

A

lymph nodes

50
Q

(T/F) Follicular B cells need T cell help to respond to antigen.

A

True

Immunology (17 decks)

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