Section 3: Antibody-Mediated Immunity & Immunoglobulins

What is antibody-mediated immunity?

Immunity resulting in soluble antibodies in blood & lymph that tag targets for destruction.

What do plasma cells do?

Release antibodies into tissue and blood.

What is the basic structure of an antibody?

4 polypeptide chains – 2 heavy chains, 2 light chains; connected by disulfide bonds.

What does the Fc region of an antibody do?

Constant region that binds to host cells.

What does the Fab region of an antibody do?

Variable region that binds antigen.

Which antibody is most abundant in serum?

IgG

Which antibody can cross the placenta?

IgG

Which antibody is found in secretions (tears, saliva, intestines)?

IgA (secretory IgA or sIgA).

Which antibody is associated with allergies?

IgE

Which antibody is a pentamer and activates complement?

IgM

Which antibody is found on B cells and activates them to start antibody production?

IgD

Describe the primary immune response.

First exposure to antigen; slower, lower antibody levels.

Describe the secondary immune response.

Subsequent exposure to same antigen; faster, stronger, higher antibody levels.