Question

matching:
match the antibody class with its description.
iga a. this class of antibody is the only one that can cross the placenta.
igd b. this class of antibody is the first to appear after activation of b cells.
ige c. this class of antibody is involved in the defense against parasitic infections and involved in allergic responses.
igg d. this class of antibody is found in very large amounts in mucus secretions.
igm e. this class of antibody is not secreted by b cells but is expressed on the surface of naive b cells.

Explanation:

• IgA is abundant in mucus secretions (e.g., saliva, tears, respiratory and gastrointestinal mucus), providing local immunity.
• IgD is mainly on the surface of naive B cells (not secreted in large amounts like other antibodies in circulation).
• IgE plays a role in parasitic infections (by recruiting immune cells like eosinophils) and allergic responses (binding to mast cells and basophils, triggering degranulation when encountering allergens).
• IgG is the only antibody that can cross the placenta (providing passive immunity to the fetus) and is also the most abundant antibody in the bloodstream.
• IgM is the first antibody produced after B - cell activation (in the primary immune response).

Answer:

IgA - D, IgD - E, IgE - C, IgG - A, IgM - B