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Immunology Tutors Review > Antibodies and Antigens- Lecture 6 > Flashcards

Antibodies and Antigens- Lecture 6 Flashcards

1
Q

Antibodies are associated with the _____ _____

A

Humoral response

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2
Q

Antibodies respond to ____ ______ ONLY

A

extracellular pathogens

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3
Q

Antibodies are produced by B cells as part of _____ _____ ____

A

ADAPTIVE immune system

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4
Q

What are the 5 main effector functions of antibodies?

A
  1. Agglutination (bind pathogens together)
  2. Neutralization of toxins (similar feature- blocks receptors from binding toxins)
  3. Activation of complement (to facilitate phagocytosis)
  4. Opsonization (to facilitate phagocytosis)
  5. Regulatory properties with production of cytokines (antibody-dependent cellular cytotoxicity) –> Initiates a T cell or inflammatory response
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5
Q

What is the structure of the antibody?

A

4 chains:
2 light- Kappa or Lambda (one or the other on each Ab)
2 heavy- Alpha, epsilon, gamma, delta, mew (mu)

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6
Q

Describe the 3 components of each chain on an antibody

A

Fab: binds Ag

Fc carries out effector functions and is found on only heavy chains

Hinges connect Fab to Fc allows binding of two antigens at a time

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7
Q

ALL Abs start as membrane-bound ___ or ___

A

IgM or IgD

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8
Q

What is the difference between membrane-bound and secretory antibodies?

A

Membrane-bound:

  • Has extra Ch domain
  • NO TAIL PIECE
  • Includes IgM and IgD (Which are all B cell receptors (BCR’s))

Secretory:

  • Tailpiece
  • Includes IgE, IgA, and IgG (this can be both secretory and membrane-bound)
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9
Q

Papain verses Pepsin. Describe Papain

A

Found in papayas!
Cleaves at the hinges
Leaves 2 separate Fab regions and one Fc region

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10
Q

Papain verses Pepsin. Describe Pepsin

A

Digestive enzyme in humans
Cleaves below hinges
Leaves one Fab region (can bind 2 Ags) and 1 Fc region that dissociates. The Fab region is denoted as F(ab’)2

Note that is you over digest with pepsin then you can get 2 Fab regions

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11
Q

Describe the Ab recognition of Ag

A

Proteins- In conformational, linear or cut (via proteolysis) forms
Nucleic Acids
Polysaccharides

*Note that T cells can only recognize protein Ags!

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12
Q

Affinity verses Avidity. Describe Affinity

A

Affinity: How tight an Ag binds to an Ab

Increases with secondary exposure

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13
Q

Affinity verses Avidity. Describe Avidity

A

Avidity: Strength of an Ag-Ab complex
Depends on affinity and valence
Increases as valence increases

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14
Q

What is valence number?

A

Valence: Number of ags that can bind to an Ab

Minimum is 2 ags for each Ab

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15
Q

Describe B cell receptors (IgM and IgD) in terms of:

Antigen binding site

Type of antigen that binds

Binding affinity

A

B Cells:
Antigen binding site: Binds to variable heavy and light chains

Type of antigen that binds: Proteins (can be any conformation), polysaccharides, lipids

Binding affinity: Higher affinity than T cells

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16
Q

Describe T cell receptors in terms of:

Antigen binding site

Type of antigen that binds

Binding affinity

A

Antigen binding site: Binds to variable alpha and beta

Type of antigen that binds: PROTEIN ONLY (linear only)

Binding affinity: Lower than B cell binding

17
Q

Pre-B cells will always make __ first

A

µ

18
Q

Immature B cells will always make ___ ___ first

A

Membrane IgM

19
Q

Mature B cells: produce membrane ____ and ____

A

IgM and IgD

20
Q

Actavated B cells can do what?

A

Maintain membrane IgM, IgD

Form secretory Abs IgA, IgG, and IgE

21
Q

For Abs secreted by active B cells IgA, IgG, and IgE what determines which one will be made?

A

Abs determination will be dependent on T cells and the cytokines they produce

22
Q

What do plasma cells do? And do they need to be activated?

A

Constant secretion of Abs (secretory only)

23
Q

Describe Isotype switching. What changes and what stays the same?

A

Causes change of HEAVY CHAIN Fc portion

Fab stays the same

24
Q

What does isotype switching require?

A

Requires cytokines for CD4+ T cells

25
Q

What are the 3 types of cells that can release cytokines to stimulate isotype swithing?

A

T cells
Macrophage activating cells
Neutrophils

26
Q

Describe the Structure, Location, and Stimulating Cytokine for the Ig: IgG (gamma)

A

Structure: Monomer

Location: Serum- highest in serum, can invade tissues

Stimulating Cytokines: IFN-gamma

27
Q

Describe the Structure, Location, and Stimulating Cytokine for the Ig: IgM (µ)

A

Structure: Pentamer with J chain

Location: Serum, naïve B cells

Stimulating Cytokines: IL-2, 4, 5

28
Q

Describe the Structure, Location, and Stimulating Cytokine for the Ig: IgE (epsilon)

A

Structure: Monomer

Location: Mast cells

Stimulating Cytokines: IL-4

29
Q

Describe the Structure, Location, and Stimulating Cytokine for the Ig: IgA (alpha)

A

Structure: Dimer with J chain + Secretory Component

Location: Mucosal areas- highest in whole body

Stimulating Cytokines: TGF-beta

30
Q

Describe the Structure, Location, and Stimulating Cytokine for the Ig: IgD (delta)

A

Structure: Monomer

Location: Naive B cells

Stimulating Cytokines: N/A

31
Q

What are the 5 functions of IgG (gamma)?

A 
**High in serum**
Phagocytosis
Can pass between mother and child
Can be secreted
Highest during secondary response
32
Q

What are the 5 functions of IgM (µ)?

A 
**Always present first**
Complement activation
Membrane bound
Highest during primary response
High avidity- low affinity
33
Q

What are the 3 functions of IgE (epsilon)?

A

Allergic response (mast cell activation)
Can be secreted
Acute inflammation and infections by worms

34
Q

What are the 3 functions of IgA (alpha)?

A

Mucosal Defense
Can be secreted and can cross endothelial membranes (GI tract as a dimer)
Transferred in breast milk)

35
Q

What is the function of IgD (delta)?

A

Only found on B cells

Immunology Tutors Review (9 decks)

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