Lecture 4, IG Structure Flashcards Preview

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Flashcards in Lecture 4, IG Structure Deck (34):
1

What are the 5 Ig isotypes?

IgM, IgG, IgE, IgA, IgD

2

Describe the structure of an Ig

2 central heavy chains, each w/ a light chain attachment via di-S bonds.
- All 4 chains have a variable and constant domain

3

What's another name for the hyper-variable regions of each chain?

CDR: complementarity-determining region

4

In the CDR, 3 hyper-variable regions combine to make a _______________.

Binding site

5

If treated w/a proteolytic enzyme, what would be the names of the resulting Ig fragments?
*Which would tell you what class of Ig it is?

- Fab (ag-binding fragment)
- Fc (crystallizable fragment- constant region)
Fc would tell you Ig class

6

Which Ig's aren't only found in monomeric form, and what form are they found in?
What's the name of their accessory protein, in each?

- Pentameric IgM
- Dimeric IgA
(both contain J chain as well)

7

If you see cell w/monomeric IgM on its surface, by definition it’s a _____________.

B cell

8

What's an epitope?
About how many AA's long do they span?

Antigenic determinant (small segment of ag where AB binds)
- Usually 6-8 AAs long (so can be lots)

9

IgA in the mucosa is found as a ___________ but in the serum it's found as a ___________.

- dimer
- monomer

10

What is the major AB of the body? Where is it mostly found?

IgA
- Mucosa

11

What's the major AB of the blood?

IgG

12

What is the normal laboratory value of serum total protein?
What portion is Ig?

- 7 g/dL (wiki; but she says 100...)
- Ig: ~1/10th of the total protein found in blood (mostly IgG)

13

What's the 1/2-life range of the Ig's?
*Which typically has the longest 1/2-life?

~2-21 days
- IgG

14

Cross-linking of which Ig on mast cell leads to degranulation? (allergies)

IgE

15

What's the name of the receptors that cells have to bind Ig's?
Which part of the Ig do they bind?

Fc receptors (e.g. Fc-epsilon, Fc-gamma, etc)
- Bind constant domain

16

By which 3 Methods do ABs mediate humoral immunity?

1. Neutralization
2. Opsonization (facilitates phagocytosis)
3. Complement Activation (phagocytosis facilitated, sometimes w/lysis)

17

What must happen when an Ig binds an Fc in order for a response to occur?

Cross-linking

18

Prior to conception, fetus relies on what Ig from mom?
Fetus first starts to develop which of its own Ig's?
What 2 come next, after birth?

- IgG
- IgM
- IgG, IgA

19

The total 1/2-life of AB's to diseases like tetanus and measles is:
a. weeks
b. months
c. years

c. years
(5-10 years for tetanus, 3,000 years for measles)

20

AB from a clone of B cells is ___________. AB from multiple clones of B cells is ___________.

- Monoclonal
- Polyclonal

21

What is IVIG?
How is it made?

- Intravenous immunoglobulin: Polyclonal AB used to treat many immune deficiencies and inflammatory dz's
- Made by taking serum from ~10K different people, isolate the serum, pool together (not known if it actually works)

22

Class-specific antigenic determinants are associated w/which part of the Ig molecule?

Constant region of heavy chain

23

How do you differentiate a T from B cell?
What about a specific type of B cell?

B cells have IgM on the surface.
- Could also look for kappa or lamba light chain to find a specific type of B cell?

24

What's the major AB in secretions (saliva, tears, breast milk)?
Be specific

Mucosal IgA (dimeric)

25

First serum AB made in an immune response?

IgM

26

What Ig plays a primary role in protecting gut or resp mucosa?

Secratory IgA

27

Predominant Ig produced in the primary immune response?

IgM

28

Predominant Ig produced in the secondary immune response?

IgG

29

Predominant Ig in external secretions as dimer? (monomer in the serum)

IgA

30

Ig found mainly on surface of B cells, only?

IgD

31

Ig involved in allergic hypersensitivities?

IgE

32

What major Ig crosses placental barrier?
Which 2 others major ones don't?

- IgG does
- IgM, IgA don't

33

What Ig has a role in mucosal immunity, but it's fcn is unclear?

IgA

34

*Compare the relative levels of each Ig class in serum.

IgG 13.5mg/dL > IgA 2.1 > IgM 1.5 > IgD 0.04 > IgE 3E-5