Immunoglobulins are antibodies produced by plasma cells classified into five types. Which set lists all five?

• A. IgA, IgD, IgE, IgG, and IgM
• B. IgA, IgB, IgF
• C. IgG, IgM only
• D. IgA, IgG, IgM

Answer: (A)

All five immunoglobulin classes are IgA, IgD, IgE, IgG, and IgM. These antibodies are produced by plasma cells and differ in location and role: IgM is the first antibody produced in a new infection and often forms pentamers that are good at clumping pathogens; IgG is the most abundant in blood and provides long-term protection, opsonization, and complement activation; IgA is the main antibody in mucosal areas and secretions; IgD mainly acts as a B-cell receptor on naive B cells; and IgE mediates allergic responses and defense against parasites. Any option that includes non-existent types (like IgB or IgF) or omits one or more of these five does not list all five.