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Immunology > Chapter 11 Antibodies (Abs) or Immunoglobulins (Igs) > Flashcards

Chapter 11 Antibodies (Abs) or Immunoglobulins (Igs) Flashcards

1
Q

Antibodies are ______

A

glycoproteins produced by plasma cells In response to antigens.

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2
Q

what kind of globulins are Antibodies?

A

gamma globulins

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3
Q

all Igs consist of four polypeptide chains made up of what?

A

two identical Light chains and two identical heavy chains held together by a noncovalent and covalent inter and intrachain disulfide bonds. Each chain consist of a variable region and a constant region.

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4
Q

Do IgM and IgE have a hinge region?

A

They do not have a hinge region.

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5
Q

What is the hinge region?

A

the proline-rich region between the CH1 and CH2 domains. confers segmental flexibility on the Ig molecule.

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6
Q

What does Papain do?

A

Cleaves IgG above the S-S bond at the hinge region, producing two antigen binding fragments and one crystalizable fragment.

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7
Q

What does Pepsin do?

A

Cleaves IgG below the S-S bond at the hinge region, hence the hinge region and interchain disulfide bonds are retained in an F(ab’)2 molecule but the Fc fragment is degraded.

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8
Q

Fab and F(ab)2 can bind to antigens without activating what?

A

Fc-dependent effector functions.

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9
Q

What does the Fc piece of the antibody do?

A

Activates complement, can bind to Fc receptors on various cells, initiates placental transfer.

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10
Q

What does the lg identical light chains consist of?

A

200-250 amino acids linked by S-S bonds to a heavy chain.

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11
Q

What are the two type of isotype classes of light chains?

A

Kappa and Lambda, A given Ig molecule always contains two Kappa or two lambda light chains but NEVER a mixture of both.

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12
Q

Each Ig molecule consist of 2 identical heavy chains: each heavy chain consist of ?

A

each heavy chain consists of 450-600 amino acids.

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13
Q

Different CH isotypes and associated Fc regions perform distinct effector functions, such as?

A

eg, complement activation, opsonization

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14
Q

What do the 3 hypervariable regions of a light chain and the 3 hypervariable regions of a heavy chain form?

A

they form the antigen-binding site.

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15
Q

What must happen to bring about neutralization and/or elimination of an antigen?

A

an antibody must bind tightly to the antigen.

this interaction is characterized by noncovalent, reversible binding.

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16
Q

What does Affinity mean?

A

how strongly an antibody is attracted to an antigen

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17
Q

What is Avidity?

A

the sum total of the strength of binding of two molecules such as antibody and antigen.

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18
Q

What is an isotype?

A

refers to the amino acid differences in the CL and CH regions that distinguish each immunoglobulin class and subclass.

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19
Q

What is an Allotype?

A

Characterized by a few amino acid differences of Ig CL and CH regions

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20
Q

What are allotypic differences used to establish?

A

Paternity and determine blood stain origins.

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21
Q

What is an idiotype?

A

these are generated by unique combination of amino acids in the variable regions of the light and heavy chains. Each idiotype is unique for the antigen specific antibody produced by a clone of B cells.

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22
Q

What is the primary function of an antibody molecule?

A

to bind antigen

23
Q

When are effector functions of antibodies initiated?

A

when antibodies bind to their specific antigens and engage other effector molecules ( comp. proteins)

24
Q

Who mediates most of the effector functions of immunoglobulins?

A

mediated by the Fc portion of the heavy chain.

25
Q

What mediates Ig neutralization ?

A

mediated exclusively by Fab binding of antigen and does not require participation of Ch regions. ( sorry this was a shitty question its the last part on page 111, look at it your self if your bitching) =o)

26
Q

When IgG binds to Dog poo and cat shit what antibody is produced!?!

A

HAHAHA you were like what????? but this is how i feel about IMMUNO…..WHO THE FUCK CARES>….. NOBODY!

27
Q

Does the Fab region have effector functions?

A

No

28
Q

What are the effector functions of the Fc region?

A

bind with macrophages and neutralization- covering bacteria with antibody

29
Q

What are Fc receptors?

A

Cell surface receptors that bind the Fc portion of an antibody molecule. they help mediate effector functions.

30
Q

What immunoglobulin is the major one in serum?

A

IgG

It is found in blood, tissue spaces and extravascular spaces.

31
Q

What does FcyRIIB express and where is it found?

A

It is found on B cells and expresses an inhibition motif, when cross linked to the BCR, it delivers inhibitory signals to the B cell blocking B-cell activation.

32
Q

What are the functions of IgG?

A

1.)opsonization 2.)Neutralization 3.)only antibody that can cross the placenta in some species.

33
Q

What is the first Ig produced?

A 
IgM
first Ig class produced both during the development of B cells and during the primary immune response.
34
Q

What is the most efficient Ig in agglutinating matter?

A

IgM

complement activation

35
Q

What are some functions of IgM?

A
  • most efficient in agglutination
  • monomeric IgM- antigen receptor BCR on naïve B-cells.
  • Neutralization of viruses and toxins
  • Opsonization- IgM is not an opsonin bc phagocytes don’t posess FcuRs, but it is a potent complement activator.
  • Predominant Ig produced by the fetus
36
Q

Is IgM and opsonin?

A

No but it is a potent complement activator

37
Q

what would an elevated IgM level in the blood of a newborn be indicative of?

A

transplacental infection

38
Q

where does synthesis of IgA occur?

A

mainly in mucosal lymphoid tissues esp GI and Resp tract

39
Q

what are the IgA forms?

A

two forms

  • Secretory IgA (sIgA) in various body secretions, present as a dimer plus a joining chain and a secretory component.
  • serum IgA is present mostly as a monomer
40
Q

What Ig is predominant in various secretions?

A

Secretory IgA ( in saliva, tears, milk etc.)

41
Q

What are some functions of IgA?

A
  • in secretions: milk, tears, saliva
  • protects mucosal surfaces by preventing attachement
  • Agglutination of antigens
  • Serum IgA is in low concentration so its a minor component of humoral immunity
42
Q

How many CH domains does IgE possess?

A

4

43
Q

IgEs Fc portion binds to what?

A

FceRs on mast cells, basophils and eosinophils

44
Q

JUST KNOW THIS!!! IgE is Heat labile at 56 C

A

IgE is Heat labile at 56

45
Q

What are some functions of IgE?

A
  • mediates immediate hypersensitivity (anaphalxis) by causing release of mediator such as histamine from mast cells. this is why its known as a reaginic antibody
  • Defense against some helminth infestations
46
Q

What is the only known function of IgD?

A

as a antigen receptor on naïve B cells. Its heat lable at 56C

47
Q

What is ADCC?

A

the killing of antibody coated target cells by nonspecific cells with Fc receptors that recognize the Fc region of the bound Ab

48
Q

who mediates most ADCC?

A

Natural Killer cells that have FcyRIII(CD16) on their surface

49
Q

what type of Fc does Macrophages and neutrophils express?

A

FcyRs and kill target cells via IgG mediated ADCC

50
Q

What type of Fc do Eosiniphils express?

A

FceRs and kill helminth parasites via IgE mediated ADCC

51
Q

what are monoclonal antibodies?

A

they are antibodies that arise from a single clone of cells are homogenous and are directed against only one epitope, such antibodies are called monoclonal antibodies (mAbs)

52
Q

what does polyethylene glycol cause?

A

cell fusion

53
Q

What does Hypoxanthine aminopterin-thymidine HAT cause?

A

kills the ones that don’t fuse

Immunology (7 decks)

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