Which immunoglobulin isotype is predominantly produced during a primary immune response and is the best indicator of acute or recent infection in serology?
- A IgG
- B IgM ✓
- C IgA
- D IgE
Correct answer: B. IgM
Explanation
IgM is the predominant antibody of the primary immune response; it appears first, has the highest molecular weight (pentamer, 900 kDa), and is the best indicator of acute infection when detected in a single serum sample. IgG predominates in secondary responses and provides long-term memory. IgA is the main secretory antibody of mucosal immunity. IgE mediates Type I hypersensitivity and elevated levels indicate atopy or helminth infection.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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