Antibodies

Question 1

What secondary effector functions do antibodies initiate? (3)

Answer 1

Complement activation, opsonisation and cell activation via specific antibody binding receptors

Question 2

Which end is the amino terminus and which end is the carboxyl terminus of an antibody?

Answer 2

The carboxyl is closest to the constant region, amino furthest from constant region

Question 3

How are the four polypeptide chains of an antibody held together?

Answer 3

Disulphide bridges

Question 4

Are antibodies symmetrical?

Answer 4

YES

Question 5

Which is Fab and which is Fc?

Answer 5

The constant part of the two heavy chains is Fc, the variable regions are Fab

Question 6

Are antibodies flexible? Why?

Answer 6

Yes so they can bind to many widely or narrowly spaced epitopes

Question 7

What regions do both light and heavy chains have?

Answer 7

Constant and variable

Question 8

Which part of the antibody is the antigen binding site?

Answer 8

The variable region

Question 9

What are immunoglobulin domains?

Answer 9

Internal intrachain disulphide bonds

Question 10

What does the Fc part do?

Answer 10

Undergoes conformational changes when antigen binds, and can perform effector functions such as activating complement

Question 11

What are the three hyper variable regions called?

Answer 11

Complementarity Determining Regions (CDR)

Question 12

Where are the CDR and what do they do?

Answer 12

At the end of the protein/line up at the end of the V domain and interact with antigen

Question 13

What is antibody affinity?

Answer 13

The strength of the total non-covalent interactions between a single antigen-binding site and a single epitope on an antigen

Question 14

What is antibody avidity?

Answer 14

The overall strength of multiple interactions between an antibody with multiple binding sites and a complex antigen with multiple epitopes

Question 15

What is antibody cross reactivity? Example?

Answer 15

Antibodies produced in response to one antigen can cross-react and bind to a different antigen of similar structure, e.g. cowpox vaccine working for smallpox

Question 16

What is difference in different classes of antibodies?

Answer 16

The constant regions of their heavy chains vary

Question 17

What are the five classes?

Answer 17

IgG, IgA, IgM, IgD, IgE

Question 18

Which classes of immunoglobulin have subclasses?

Answer 18

IgG and IgA

Question 19

What are the two types of light chain?

Answer 19

Kappa and lambda

Question 20

Which classes have three constant heavy domains?

Answer 20

IgG, IgA, IgD

Question 21

Which classes have four constant heavy domains?

Answer 21

IgM and IgE

Question 22

How many subclasses in IgG?

Answer 22

4

Question 23

How many subclasses in IgA?

Answer 23

2

Question 24

What is the difference in subclasses? (3)

Answer 24

Variance in the hinge region (e.g. loads of disulphide bonds between the heavy chains), ability to activate complement (IgG4 doesn’t) and effector function domains

Question 25

Which is the only class of immunoglobulins that can move across the placenta?

Answer 25

IgG

Question 26

Which is class of immunoglobulins is a major activator of the complement pathway?

Answer 26

IgG

Question 27

Which is the most abundant class of immunoglobulins?

Answer 27

IgG

Question 28

What are the subclass numbers representative of?

Answer 28

Abundance, 1 being the most abundant

Question 29

What is the difference between IgA in blood and scripted?

Answer 29

Monomer in blood, dimer in secretions

Question 30

Main function of IgA?

Answer 30

Protect mucosal surfaces

Question 31

Which is the second most abundant class of immunoglobulins?

Answer 31

IgA

Question 32

What produces IgA?

Answer 32

Plasma cells (activated B cells)

Question 33

Describe the process of IgA secretion

Answer 33

The IgA is produced by a plasma cell (activated B cell) and then binds to the Poly-Ig Receptor on the basolateral membrane of the epithelial cell. The poly-Ig receptor is cleaved which leaves the secretory component attached to the dimeric IgA.

Question 34

What does the secretory component of a secreted IgA dimer do?

Answer 34

Helps protect the secreted antibody from degradation

Question 35

What is the stand out feature of IgM?

Answer 35

Pentameric

Question 36

Which is the first Ig produced after exposure to an antigen?

Answer 36

IgM

Question 37

What are IgM useful for?

Answer 37

Agglutination

Question 38

Can IgM activate complement?

Answer 38

Yes

Question 39

What is the problem with IgD?

Answer 39

Not useful for fighting infection directly

Question 40

What is the main purpose in IgD?

Answer 40

Involved in B cell development and activation

Question 41

What is IgE useful for?

Answer 41

Fighting parasitic infections and allergic disease

Question 42

What does IgE bind to?

Answer 42

High affinity Fc receptors of mast cells and basophils

Question 43

What does IgE do?

Answer 43

Triggers mast cell activation and histamine release. Fc part binds to mast cell, allergen binds to Fab and triggers mast cell activation and histamine release.

Question 44

What are atopic individuals?

Answer 44

Individuals more susceptible to making IgE and having allergic reactions

Question 45

Which antibodies are generally found in blood?

Answer 45

IgG and IgM

Question 46

Which antibodies are generally found in extracellular fluids?

Answer 46

IgG

Question 47

Which antibodies are generally found in secretions?

Answer 47

IgA

Question 48

Which antibodies are generally found in the foetus?

Answer 48

IgG

Question 49

Which antibodies are generally found in mast cells below epithelia?

Answer 49

IgE

Question 50

What type of antibodies do NK cells work well with?

Answer 50

IgG