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MICB 202 > Midterm Part 4 > Flashcards

Midterm Part 4 Flashcards

1
Q

What is are the 3 signals needed to activate T cells?

A

1: Antigen specificity: MHC/peptide TCR
- When it’s the right match, leads to CD3-mediated signalling to nucleus

2: co-stimulation B7 (CD80/CD86)/CD28: Necessary for full T cell activation
• clonal proliferation
• acquisition of effector function

3: cytokines
- DC’s produce IL-12, IL-18
- IL-12, IL-18 influence T cell function (both CD4 and CD8)

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2
Q

What is the result of signal 1 and 2 in activating T cell?

A
  • IL-2 production of clonal proliferation

- Up-regulation of CD40L

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3
Q

What happens if a Th cell is instructed to produce IFNy?

A

It will lead to activation of macrophages

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4
Q

What are the effector molecules of a CD4 T cell? What is the function of a CD4 T cell?

A
  • CD40L, IL-2, IFNy

- to help macrophages, B cells and CD8 T cells

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5
Q

What is the result of IL-2 production?

A

Clonal proliferation

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6
Q

What is the result of IL-12 and IL-18 production from the DC?

A

T cells will perform the effector function

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7
Q

What are the five important features of the adaptive immune system?

A
  1. Diversity
  2. Specificity
  3. Inducibility
  4. Memory
  5. Self-tolerance
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8
Q

What is the structure of a BCR?

A

Mlg: membrane bound immunoglobulin for antigen binding

Iga and Igb:m signalling partners

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9
Q

What kind of Ig does an immature B cell express?

A

IgM+

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10
Q

What kind of Ig does a naive, mature B cell express?

A

IgM+ and IgD+

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11
Q

How do B cells undergo negative selection? What is the purpose of this?

A
  • Any BCR that recognizes self-antigens in the bone marrow is deleted
  • to eliminate potentially self reactive B cells
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12
Q

What is the role of the BCR?

A

BCR is responsible for antigen binding and determines the antigen specificity of the B cell

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13
Q

Where does the B cell begin to express the BCR and costimulatory proteins?

A

In the bone marrow

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14
Q

What is the Igα/Igβ subunit analogous to in the T cell?

A

CD3

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15
Q

What will happen if a BCR binds to an antigen while still in the bone marrow?

A

the Igα/Igβ subunit will send signals for it to die (clonal deletion)

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16
Q

Why do B cells not need to go through positive selection?

A

They don’t need to interact with MHC like the T cell does

17
Q

Where do B cells go once they have matured?

A

The spleen and the lymph nodes

18
Q

What is the structure of a BCR?

A

2 identical heavy (H) chains and 2 identical light (L) chains. Each of the immunoglobulin H and L chains has one V region (V = variable) and one C region (C = constant). The VH (variable region of the Heavy chain) and VL (variable region of the Light chain) regions combine to form an antigen-binding pocket. There are two antigen-binding sites per BCR (or immunoglobulin molecule)

19
Q

What is the name for immunity due to antibodies?

A

Humoral immunity

20
Q

What is the difference between mlgs and slgs?

A

The amino acid sequences at the carboxyl-terminus of the H chain.

  • For mIg, the amino acids are hydrophobic so that the polypeptide is anchored in the membrane when the vesicle fuses with the plasma membrane.
  • For sIg, the amino acids tend to be hydrophilic so that when the vesicles with the plasma membrane, the antibodies are released into the extracellular fluids
21
Q

True or false: BCR’s exist on B cells, but not plasma cells or T cells

A

True

22
Q

Can T cells recognize tertiary epitopes? Why or why not?

A

T cells can only recognize linear sequences, and this is because of the MHC complex
- it is limited to binding in the MHC binding cleft (unlike BCR, which can bind to soluble antigen)

23
Q

What roles do antibodies play in immunity? What determines which role an antibody will play?

A
  • Neutralization
  • Opsonization
  • Complement activation

The constant region of the heavy chain

24
Q

What are the five types of Ig’s?

A

IgM, IgD, IgG, IgA, IgE

25
Q

When a mature B cell is not activated, what is it doing?

A

Circulating through blood, lymph, and lymph organs

26
Q

What are the two signals that B cells need to be activated? What is the third signal?

A
  1. Antigen recognition
    • B cell recognizes Ag, cross linking occurs, clusters of Iga/IgB form
    • B cell internalizes the Ag and presents it on MHC II
  2. Costimulation from the T cell
    • an ACTIVATED T cell binds to the MHC II peptide complex
    • CD40L on T cell joins CD40 on B cell
      1+2= proliferation and effector function
  3. cytokines: class switching
27
Q

What is the purpose of the hyper variable region on the antibody?

A

contributes significantly to the antigen-binding site and are the part of the antibody that contacts the antigen

28
Q

The constant regions on the H and L chains are _______ specific

A

Specific

MICB 202 (26 decks)

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