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Zach- Immunology > Lecture 5: Abs and Ags > Flashcards

Lecture 5: Abs and Ags Flashcards

1
Q

Of the three Ag recognition structures what makes Ab unique and far superior?

A
  1. recognize widest range
  2. highest amount of ability to discriminate
  3. bind with the greatest strength
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2
Q

What is serum?

A

blood that lacks coagulation factors but contains other plasma proteins

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3
Q

What is an anti-serum?

A

serum that contains detectable amounts of Ab bound to particular Ag

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4
Q

The “V” region on the Ab is made of what and has what task?

A
  1. amino-terminal variable region

2. participates with Ag recognition

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5
Q

The “C” region on the Ab is used to do what?

A
  1. specifically the C region on heavy chains is used to direct effector functions
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6
Q

What forms the antigen binding site?

A

Vheavy and V light chain of the Ab

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7
Q

What type of C region will a PM bound Ab have that would be absent from a secreted Ab?

A

A PM bound Ab would have to have a A heavy chain region that acted as an anchor to the PM.
-the heavy chain region is responsible for mediating effector functions

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8
Q

Does the light C chain play a role in effector mediation or attaching directly to the PM?

A

no

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9
Q

What happens to IgG when it is treated with Papain?

A
  1. 2 identical structures of Fab form, which are able to recognize Ag as the Vh and Vl are still intact
  2. the other structure is Fc, which self-associates and can then form a crystalline lattice
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10
Q

What regions are contained within the Fab, after treatment with Papain?

A
  1. Vh and Vl to recognize the Ag
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11
Q

What regions are associated within the Fc after treatment with Papain?

A
  1. Ch2 and Ch3

which are part of the heavy chain regions.

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12
Q

In order to produce the Fab and Fc regions where specifically will papain act to cleave?

A

above the hinge region. leaving the hinge on the Fc portion with the heavy chains

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13
Q

What is produced if IgG is treated with pepsin?

A
  1. cleavage occurs below the hinge, keeping it intact
  2. produces two identical binding sites that are joined by the hinge.
  3. produces peptide fragments of what could have been the Fc region.
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14
Q

Where are regions of hypervariability located on the Ab?

A
  1. located on the Vlight and Vheavy regions (Ag recognition site)
  2. act like protruding fingers that create a specific 3-D binding site for the Ag
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15
Q

Which of the CDRs is the most variable?

A
  1. CDR3.

2. complementarity determining regions that are formed by the Vh and Vl to bind Ag

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16
Q

How are Ab divided into separate subclasses?

A
  1. characterized by differences in the structure of the Heavy chain C regions
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17
Q

Why is it that certain subtypes/subclasses can perform specifically different effector functions?

A

1.The difference in the heavy chain C regions affects which Fc receptors are able to be activated on different cells.

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18
Q

What distinguishes the different types of light chains on Abs?

A

the class of either kappa or lambda is distinguished by the C regions. we have no idea what the difference of these is for.

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19
Q

What is an allotype?

A

polymorphic variant on the C region and Ig heavy and light chains. this varies from the original sequence in the same species

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20
Q

What is a hybridoma?

A

a fused normal B cell and tumor cell, that are grown in conditions where all other cells are killed

21
Q

What are hybridomas able to secrete?

A

monoclonal antibodies that are specific to binding with the Ag of interest

22
Q

What are the practical application of monoclonal bodies?

A
  1. ID phenotypic markers unique to particular cell type
  2. immunodiagnosis
  3. tumor ID
  4. therapy
  5. functional analysis of cell surface and secreted molecules
23
Q

What type of immunoglobulins are expressed on a stem cell at the beginning of B cell maturation?

A

none

24
Q

What type of immunoglobulins is produced on a pre-B cell during B cell maturation?

A
  1. micro chains

2. pre-B cell receptors which form from micro chains interacting with surrogate light chain proteins

25
Q

What immunoglobulin is expressed on an immature B cell?

A
  1. membrane IgM
26
Q

What immunoglobulin is expressed on a mature B cell?

A
  1. IgM and IgD
27
Q

What causes a mature B cell to become an antibody secreting cell?

A

1.activation via Ag or other stimuli

28
Q

What changes take place in transition from a mature B cell to an antibody secreting B cell?

A
  1. increase production of secreted Ig

2. heavy chain isotype switching, altering the IgM, IgD expression

29
Q

Is spatial arrangement of different epitopes on a protein molecule able to effect the binding of Ab?

A

yes, produces and overlapping or non-overlapping case

30
Q

What is an overlapping determinant?

A

the binding of an Ab to the 1st determinant is able to influence the binding of the Ab to a second determinant

31
Q

What is a non-overlapping determinant?

A

the determinants are located far enough from one another that Ab binding does not influence one another.

32
Q

When is a conformational determinant able to bind with the Fab region of the Ab?

A

only when it is properly folded. If the protein denatures the determinants will not be able to interact with the CDR of the Ab

33
Q

When is a linear determinant able to be recognized and bound by an Ab?

A

The protein will contain one or more regions that will be able to interact with the CDR. This sequence can allow for recognition in the folded or denatured state.

34
Q

When is a neoantigenic determinant most readily recognized and bound by an Ab?

A

The protein undergoes sometype of post-synthetic modification that exposes a determinant that can bind with the CDR of the Fab region on the Ab

35
Q

What is affinity?

A

strength of the binding between a single combining site of an Ab and an epitope of an Ag

36
Q

What does a low Kd value represent in terms of affinity?

A

1.higher affinity as a complex will form with low [Ag] and [Ab]

37
Q

What is avidity?

A

the strength of attachment between the Ag and Ab, which can increase with increasing sites of interaction

38
Q

Would a low affinity IgM molecule of low affinity IgG molecule have a stronger binding?

A

the IgM as it has multiple points of attachment, which in summation produce high avidity.

39
Q

Which type of Ab will have a low level of avidity?

A

Ab that are only able to bind with one interaction

40
Q

Which type of Ab will have a high level of avidity?

A

Ab that are able to bind multiple Ag binding sites, which summate to increase the strength of binding.

41
Q

What, if formed, produces a high risk of generating an immune complex disease?

A
  1. immune complex that forms in tissues and trapped there, causing inflammation
    - - polyvalent antigen and specific antibody that interact
42
Q

What is cross-reaction?

A
  1. Ab produced against one Ag that bind to a structurally similar Ag.
43
Q

Is it possible for a cross-reaction to occur with self-antigens?

A

yes, this could then contribute to immunologic disease

44
Q

During a primary immune response would a B cell have a Kd=10^-7 or Kd=10^-11? Which would be true for a secondary?

A
  1. primary: 10^-7 higher concentration to generate immune response
  2. 10^-11, lower concentration, recognized earlier
45
Q

Where are a majority of the effector functions of Ab found?

A

the Fc region, and each perform specific tasks

46
Q

During B cell affinity maturation, what changes are taking place in the structure of the Ab?

A
  1. The Vheavy and V light regions are altered with changes specificity, but the C region remains the same to produce the same effector response.
    Generally Ag recognition is increased
47
Q

What happens to Ab that undergo changes to increase the number of secreted Ab?

A
  1. secreted Ab production increases
  2. membrane Ab production decreases
  3. alters the C region from PM sequence to secreted sequence.
48
Q

What happens to Ab that undergo isotype switching?

A
  1. the V region does not undergo changes

2. the C region is changed, so that it can activate different effector proteins

Zach- Immunology (10 decks)

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