8. Memory and Specificity of the Antibody Response

Question 1

What class of antibody is indicative of an early immune response?

Answer 1

IgM

Question 2

What class of antibody provides life-long immunity to an antigen?

Answer 2

IgG

Question 3

What is the anamnestic response?

Answer 3

• secondary response

- second or subsequent exposure to an antigen already encountered

Question 4

Why is antibody production faster and more prolonged in the secondary response?

Answer 4

• memory B cells and T cells
• persist in the body for years
• are in a pre-activated state
• have high affinity receptors and the ability to switch Ig production from IgM to IgG

Question 5

Name the gene segments that code for the immunoglobulin heavy chains.

Answer 5

Variable region genes

• V(sub H) = variable heavy
• D = diversity
• J(sub H) = joining

Constant region genes
- C mu, delta, gamma, epsilon, alpha

Question 6

Name the gene segments that code for the immunoglobulin light chains.

Answer 6

• V kappa, lambda
• J
• C kappa, lambda

Question 7

How is the immune system able to produce enough antibody molecules against the millions of antigens in our environment with a limited amount of DNA?

Answer 7

• genes coding for antibody molecules are constructed by choosing selected segments and joining them together
• modern germ line theory

Question 8

Why can a single B cell make only one antibody?

Answer 8

• due to a particular gene combination/sequence?

Question 9

How does the antibody production of a B cell switch from IgM to IgG?

Answer 9

• removal of DNA segment by enzyme activity and non-homologous end joining of DNA at switch region results in a different gene sequence and thus a different immunoglobulin antibody expression/production
• B cells producing IgM still have the other C gene codes after C mu, transcription just stops after C mu.

Question 10

If a person develops a Streptococcal throat infection, how is that person’s immune system stimulated to produce antibodies against antigens on Streptococcus bacteria, and not against antigens on another type of bacteria?

Answer 10

• specificity at both gene level and cellular level
• only the B cells that bind to the specific Ag are stimulated to divide and mature into antibody-producing cells.
• Gene level = Immunoglobulin class switching via cytokines