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Sem 2: Immuno > Lymphocytes and their receptors - Bittencourt > Flashcards

Lymphocytes and their receptors - Bittencourt Flashcards

1
Q

What are the 3 major types of lymphocytes?

A

T cells

B cells

NK cells

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2
Q

Which cell regulates adaptive immunity and is responsible for cellular immunity?

A

T cells

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3
Q

What are B cells responsible for?

A

Antibody production

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4
Q

When does T cell development begin?

A

Before birth

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5
Q

T cells that express a beta chain become _______

A

ab T cells (most common)

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6
Q

T cells that express gamma or delta chains become _____

A

gamma delta T cells - involved in innate and adaptive, less common

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7
Q

ab T cells

A

most common

involved in adaptive immunity

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8
Q

What part of the immune system do NK cells play a role in?

A

Mostly innate!!

Does participate in ADCC pathway in adaptive immunity

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9
Q

What segments are found on the beta chain of TCR receptors?

A

VDJC segments

  1. Variable region
  2. Joining region
  3. Constant region
  4. Diversity segment
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10
Q

What segments are found on the alpha chain of TCR receptors?

A

VJC segments

  1. Variable region
  2. Joining region
  3. Constant region

** no diversity segment

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11
Q

What segments are found on both alpha and beta chains on TCR’s?

A

variable region and constant region

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12
Q

How does TCR gene rearrangement begin?

A

With rearrangement of beta chain genes in pre-T cells (thymocytes)

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13
Q

How is a ab TCR assembled?

A
  1. Beta chain assembled first
  2. Random joining of Diversity and Joining segments (DJ-beta)
  3. Random linking of DJ-beta segment with Variable segment (DJV-beta segment)
  4. Forms variable region of beta chain

Then alpha is assembled!!

  1. Variable segment and Joining segment make complete alpha chain variable region (VJ- alpha segment)
  2. VJ-alpha segment then joins with C-alpha region = VJC alpha chain
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14
Q

What is RAG1-RAG2 complex?

A

Helps with the recombination of VDJ segments

Cleaves the VDJ segments

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15
Q

What does DNA-dependent protein kinase do?

A

excises the intervening DNA to increase diversity of TCRs

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16
Q

What does terminal deoxynucleotidyl transferase do?

A

Reconnects V and J segments and adds random nucleotides within a coding joint

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17
Q

Where does selection of T cells take place?

A

In the thymus - positive and neg selection

18
Q

What causes thymocytes to undergo apoptosis?

A
  1. no TCR present
  2. Non functional TCR

= apoptosis

19
Q

What is positive selection of T cells?

A

a test to see if new TCRs can bind to MHC molecules

only T cells that bind MHC pass positive selection, if not they undergo apoptosis

96% of Thymocytes fail positive selection

20
Q

Which cells are able to migrate from the thymus?

A

only non-self-reactive T cells can leave

this avoids autoimmunity

21
Q

What is the result of T cells that bind STRONGLY to MHC/self antigen complexes on APCs?

A

Failed negative selection - Apoptosis

22
Q

What is the role of Autoimmune Regulator gene? (AIRE gene)

A

enhances negative selection in the thymus, prevents autoimmunity

helps detect self reactive T cells to kill them ASAP

induces expression of antigens found in other tissues of the body

23
Q

If a thymocyte has high affinity for an MHC II molecule what happens?

A

The thymocyte that is CD4+/CD8+ will turn off the CD8+ gene and begin to solely express CD4+

24
Q

If a thymocyte has high affinity for an MHC I molecule what happens?

A

The thymocyte that is originally CD4+/CD8+ will turn off the CD4+ gene and begin to solely express CD8+

25
Q

What are the CD4+ Th cells?

A

Th1, Th2, Th17, Treg

26
Q

Where are B cells produced?

A

In bone marrow

27
Q

Who has more receptors, T cells or B cells?

A

B cells

28
Q

How many binding sites do B cells have? T cells?

A

B cells have 2 binding sites

T cells have 1 binding site

29
Q

How many polypeptide chains are on a BCR?

A

4 polypeptide chains

  • 2 identical heavy chains
  • 2 identical light chains

A constant and variable region in each chain

30
Q

What segments are found on the heavy chain of BCRs?

A

VDJ segments

  1. Variable segment
  2. Diversity segment
  3. Joining segment
31
Q

What segments are found on the light chain of BCRs?

A

VJC segments

  1. Variable segment
  2. Joining segment
  3. Constant segment
32
Q

What determines the type of heavy chain on BCR?

A

constant segment

33
Q

What is first to appear on pro-B cells?

A

Heavy chains D and J

  1. Diversity and Joining
34
Q

How are BCRs assembled?

A

Heavy chain assembled first

  1. D and J segment join
  2. V segment joins DJ segment = VDJ segment
  3. alpha and beta Poly-Ig chains join

Then light chain forms

  1. V and J segments join = VJ segment
35
Q

When are light chains rearranged?

A

at the pre-B cell stage

36
Q

what Igs are found on a mature B cell?

A

IgM and IgD

but IgD has no function

37
Q

What occurs if a immature b cell is stimulated?

A

leads to cell death or anergy, state of no response

38
Q

When is a B cell at full maturity?

A

When IgD is expressed with IgM on the surface of the B cell

39
Q

Which chain on a BCR contains a diversity segment?

A

only the HEAVY chain

40
Q

How are B cells eliminated?

A

Through negative selection or clonal deletion

Sem 2: Immuno (17 decks)

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