Myeloma and paraproteins (not done)

Question 1

What are immunoglobulins produced by?

How do they exist in the body?

Answer 1

Produced by B cells - mainly by Plasma cells

Most immunoglobulins exist bound to cells themselves but they are soluble and exist in the plasma as well (which is what we measure)

Question 2

In what 2 ways can antibodies stop nasty things

Answer 2

They can either:

• act directly on the pathogen
• flag the pathogen for other componenrts of the immune system

Question 3

Describe the structure of an immunoglobulin

Answer 3

Y shaped

2 heavy chains

2 light chains

Variable domains / FAB (binding site)

Fc portion (constant bit)

Question 4

What part of an Ig determines:

a) the target of an antibody
b) the subclass of an antibody

Answer 4

a) variable domain
b) Fc portion (thus the heavy chain is specific to each type)

Question 5

What are the 5 different heavy chains and the antibodies they correspond to?

Answer 5

Gamma - IgG

Alpha - IgA

Mu - IgM

Delta - IgD

Epsilon - IgE

Question 6

Describe the function of IgM

Answer 6

IgM constitutes the initial phase of antibody production

In the circulation - they exist as a pentamer (5 IgMs stuck together)

Question 7

What are the main features of IgG?

Answer 7

IgG most prevalent antibody (75%)

Provides the majority of antibody based immunity against invading pathogens

Its the only immunoglobulin that can cross the placental membrane

Question 8

WHat is the function of IgA?

Answer 8

Found in mucosal areas, such as the gut, respiratory tract and urogenital tract, and prevents colonization by pathogens

Question 9

What are the main features of IgE and IgD?

Answer 9

IgE

Main role is in immune response to parasites

Also behind hypersensitivity

IgD

not particularly relevant

Functions mainly as an antigen receptor on B cells that have not been exposed to antigens

Question 10

What are the 2 types of light chains?

What determines the type that is made?

Answer 10

Kappa or Lambda

Each B cell randomly selects to produce one or the other - so theres roughly equal proportions of Kappa and Lambda light chains

Each B cell will only produce that one type of light chain, with one specificity

Question 11

Which Ig levels are commonly measured and what are their normaly ranges?

Answer 11

IgG = 6-15 g/L

IgA = 1-4.5 g/L

IgM = 0.5-2.0 g/L