21. The Immune System

The specificity of an antibody is determined by the

(a) Fixed segment

(b) Antigenic determinants

(c) Variable region

(d) Size of the antibody

(e) Antibody class

Which of the following is not involved in the activation of a B cell?

a. Antigen

b. Helper T cell

c. Cytokine

d. Cytotoxic T cell

Explain how active immunity and passive immunity differ.

The clonal selection theory states that:

Define antibody. Using an appropriately labeled diagram, describe the structure of an antibody monomer. Indicate and label variable and constant regions, heavy and light chains.

Match the following antibodies with the correct definition.

____IgD     

____IgM     

____IgG     

____IgA     

____IgE

a. Antibody found in secretions

b. Most common antibody; crosses the placenta

c. Antibody involved in allergies and parasitic infections

d. Pentamer and potent agglutinating agent

e. Antibody bound to the B cell plasma membrane

Ted finds out that he has been exposed to measles. He is concerned that he might have contracted the disease, so he goes to see his physician. The physician takes a blood sample and sends it to a lab for antibody levels and titers. The results show an elevated level and activity of IgM antibodies to rubella (measles) virus but very few IgG antibodies to the virus. Has Ted contracted the disease?

Terrence has severe asthma and allergies, and is placed on a medication that blocks the functioning of IgE. How would this medication alleviate his symptoms?

Name the five classes of immunoglobulins. Which is most likely to be found attached to a B cell membrane? Which is most abundant in plasma? Which is important in allergic responses? Which is the first Ig to be released during the primary response? Which can cross the placental barrier?