Question

IgD antibodies comprise what percentage of serum and serve what primary function?

Options

• ~0.002%; mediates allergic reactions

• ~20%; provides mucosal protection

• ~7%; activates complement

• ~1%; found on B-cell surface as a receptor

Answer 1

IgD represents approximately 1% of serum and is primarily found on the B-cell surface where it functions as a receptor. It plays an important role in regulating B-cell activation and has a minimal presence in the bloodstream compared to other immunoglobulin classes.