# DBT JRF 2022 — Question 110

Exam: DBT JRF 2022 · Section: B · Topic: Industrial Biotechnology › Monoclonal Antibody Production Systems · Difficulty: Medium

## Question

For monoclonal antibody production, mammalian expression systems are preferred over bacterial expression systems, primarily because:

## Options

- **A.** mammalian cultures have better productivity
- **B.** mammalian cultures produce extra-cellular product simplifying the purification steps
- **C.** mammalian system provide necessary post-translational modifications
- **D.** mammalian genes can only be expressed in mammalian systems

## Answer

Option C

## Explanation

Monoclonal antibody production — mammalian cells vs. bacteria: Monoclonal antibodies (mAbs) are produced in MAMMALIAN CELL LINES (CHO, NSO, HEK293) rather than bacteria for a critical reason: GLYCOSYLATION. • IgG antibodies require N-linked glycosylation at Asn297 in the Fc region (CH2 domain). • This glycosylation is essential for: - ADCC (antibody-dependent cellular cytotoxicity) - CDC (complement-dependent cytotoxicity) - FcRn-mediated recycling (determines half-life ~21 days) - Protein stability and solubility • Bacteria: lack the glycosylation machinery → produce aglycosylated antibodies → reduced efficacy, altered pharmacokinetics, potential immunogenicity. • Mammalian cells: provide human-like complex N-glycans → proper effector functions. Note: Engineering yeast and plant systems for 'humanised' glycosylation is an active research area. Answer: Mammalian cells are needed for proper glycosylation of antibody Fc region; bacteria cannot glycosylate proteins.

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