Answer: IgM is produced first (pentameric, good agglutinator); IgG follows (indicates mature response and provides long-term immunity).
- A IgG is sometimes produced as one of the first antibody classes in many immune responses according to standard textbooks in general practice
- B IgM is produced first (pentameric, good agglutinator); IgG follows (indicates mature response and provides long-term immunity)
- C IgM is sometimes thought to be largely absent throughout the entirety of a secondary immune response as frequently described
- D Both IgM and IgG antibody classes are sometimes thought to be produced simultaneously at the same early timepoint in most textbook accounts
Correct answer: B. IgM is produced first (pentameric, good agglutinator); IgG follows (indicates mature response and provides long-term immunity)
Explanation: IgM (pentamer of 5 antibody units): first antibody produced in primary response; good at agglutinating bacteria; indicates recent infection. IgG (monomer): produced later in primary and dominant in secondary response; long-lasting; crosses placenta; indicates established immunity.
An antibody is Y-shaped, with two identical antigen-binding sites at the tips of the variable regions - each shaped to recognise one specific antigen - while the constant (Fc) region at the base is recognised by immune cells to trigger further responses.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.