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Flashcards in Immunoglobulin Deck (58):
1

In what two situations would you see a gamma -globulin band on electrophoresis?

1. Hyper-immunized
2. Multiple mylenoma (plasma cell tumor)

2

Papain digestion of the Ig results in what?

1. 2 Fab fragments- antigen binding components
2. 1 Fc fragment- effector portion of the Ig

3

What is an isotype?

a distinct form the Ig heavy chain (mu, alpha, gamma, delta, epsilon) or the light chain (lamda or kappa) present in all members of a species

4

Which isotypes can be readily found in normal sera?

All of them (but E and D in trace amounts)

5

What is an allotype?

Genetic variants in the constant regions of Ig that are inherited in an allelic manner. This varies by member of a species.

6

____________is the same for all members of a species while ______________differs amongst members of the same species.

Isotype; allotype

7

What is an idiotype of an Ig?

a unique antigenic specificity conferred in the variable region of the Ig which distinguishes it from all other antibodies.

8

What antibodies will have the same idiotype?

those that arise from the same B-cell founder clones

9

_______________can be detected in serum, while ________ cannot be detected in serum due to their extremely low frequencies.

Isotype; idiotype

10

In what people are you actually able to detect idiotypes in serum?

Patients with B-cell clonal expansion

11

What is the level of IgG in serum?

12-14 microg/ml

12

What percent of serum is IgG?

80%

13

What are the major sites for IgG?

intravascular and extravascular (tissue)

14

What is the half life of IgG?

23 days (IgG3 is only 7)

15

Where are IgA found?

Intravascularly and In secretions

16

Which Ig contains J and S chains?
Which Ig only contains J chains?

J+S = IgA
J= IgM

17

Why is the molecular weight of IgM significantly more than the other Ig?

It exists as a pentamer which is why it is also mainly intravascular (too big to get into tissue)

18

Where are IgD found?

on mature B-cells (with IgM)

19

Where are IgE found?

on mast cells and basophils

20

What antibody is best at binding FcR? What does this allow it to do?

IgG-> recycles the antibodies to maintain constant serum levels

21

What antibodies can induce ADCC?

IgG

22

What antibodies are best at neutralizing toxins?

IgG

23

What antibodies can be found in breast milk?

IgG and IgA although IgG can also cross the placenta

24

Which antibodies have antiviral functions?

IgG and IgA

25

Which antibodies are antibacterial?

IgG and IgA (with the assistance of lysozyme)

26

Which antibodies are agglutinators?

IgM is the best (then IgA, and a tiny bit IgG)

27

Which antibodies are best at fixing complement?

IgM

28

Which antibodies can degranulate mast cells?

IgE

29

What is agglutination?

Organized clumping of antigen

30

What test uses hemoagglutination to do blood typing tests?

Coomb's test where there is agglutination of anti-RBC coated RBCs

31

IgM coated antigens can readily be __________________ by phagocytes if they are coated with __________________.

opsonized; complement C3b

32

What are the three major reasons why IgG are the best at neutralizing toxins and small pathogens like viruses?

1. high affinity
2. high serum levels (and high tissue levels)
3. long half life

33

What is the main strategy of IgG to keep viruses from infecting cells?

block their cell attachment site

34

Once a target is coated with _________ or _________ macrophages can readily engulf the "opsonized target" because they have _____ and _____ receptors.

IgG or C3b because they have Fc and complement (CR1) receptors

35

The complement receptor on the macrophage is _______ whereas the complement receptor on the B-cell is __________.

CR1; CR2 (CD21)

36

What is ADCC?
What antibody is best at inducing it? Why?

antibody-dependent cell mediated cytotoxicity.
IgG is best at inducing it because it can bind to FcR.

37

What four cell types have FcR that can engage IgG-target complexes?
Which 2 release perforins?
Which 2 release TNF?

1. macrophages- TNF
2. basophils
3. NK cells- perforin
4. eosinophils- perforin

38

Monoclonal Abs are being used in clinic to target and destroy tumor cells in the body. They do so via_____________________.

Antigen-dependent cell-mediated cytotoxicity

39

By what age do IgG and IgA become dominant over IgM?

4 years of age

40

Maternal ______ crosses the placenta but the serum levels in the baby drop by __________.

IgG; 6 months

41

The first Ig the baby will make is ______ which plateaus at________ years of age.

IgM, 1-2 years old

42

Which cell produces IgA heavy and light chains?
Which cell produces J-chains?
Which cell produces Poly-IgR?

Plasma cells produces IgA heavy and light chains and the Jchain

Epithelial cells produce the Poly-IgR chain

43

What feature of IgA increases its avidity?

its dimerization

44

What is the major role of IgA?

to neutralize toxins (can't bind complement or do ADCC)

45

What is the most common immunodeficiency disease (freq 1:500)?

Selective IgA deficiency- GI, respiratory, ear infections (because IgA is the antibody in secretions

46

What is passive immunization?

Xenogenic anti-pathogen or anti-toxin is transferred from 1 species to another (ex. horse or sheep anti-venom)

47

What is the only real use for passive immunization anymore?

anti-venom to snake or spider bites (infect horse or sheep with venom, collect their antibodies and inject into the human)

48

What are three advantages of passive immunization?
What is the major disadvantage?

Advantages:
1. pre-made and fast
2. inexpensive
3. usually pretty effective
Disadvantage:
It can lead to serum sickness because the immune system will make antibodies to the horse antibodies

49

What type of hypersensitivity is frequently caused by passive immunization?

Type III- immune complex hypersensitivity because the immune system makes antibodies to the immunizations antibodies --> serum sickness

50

What is given as a plasma protein replacement therapy for immunodeficient patients?

Polyclonal IVIG (usually for IgG)

51

What if IVIG used for?
What type of immunity does it confer?

it is given to maintain adequate antibody levels to prevent infection.
It confers passive immunity and is transferred human to human so there is less chance of serum sickness

52

How frequently does treatment of IVIG need to be given? Why?

every 3-4 weeks because the half-life of IgG is 23 days.

53

What diseases are treated by IVIG?

1. Immunodificiencies
2. pediatric HIV
3. lymphoprolifative disease
4. Kawasaki's diseas
5. Guillian-Barre

54

Why can IVIG be used to treat autoimmune disorders?

IgG is used to overload the immune system because it used FcRN to keep serum levels equal. By adding IgG, more of the "bad" antibodies (autoreactive) will be gotten rid of and the "good" will be recycled

55

What are four way by which IVIG may work?

1. binding inhibitory Fc regions
2. binding FcR on macrophages to recycle to pathogentic Ab can bind
3. Complement consumption
4. engagement of anti-idiotypic networks

56

What are monoclonal antibodies and how can they be produced?

They are antibodies specific for one antigen. They can be produced by:
1. by immortalized plasma cells in the bone marrow
2. recombinant engineering

57

Why may monoclonal antibodies be more safe than IGIV passive therapy?

IVIG uses Ab from a donor, whereas the Ab of monoclonal therapy are genetically engineered in a lab. There is less likelihood of transferring donor infections

58

What is the difference between a chimeric Ab and humanized Ab when engineering Ab via monoclonal Ab therapy?

Chimeric- The Fab fragments belong to mice but the Fc belongs to humans to reduce chance of serum sickness
Humanized- HV regions are mice, the rest of the Ab is human