Serum angiotensin-converting enzyme (ACE) is elevated in sarcoidosis. The biochemical basis for this is ACE being produced by which cell type that proliferates in sarcoid granulomas?

• A Activated macrophages/epithelioid cells forming the granuloma ✓
• B T lymphocytes within granulomas
• C Endothelial cells responding to hypoxia within granulomas
• D Plasma cells secreting immunoglobulins and ACE as a byproduct

Explanation

Angiotensin-converting enzyme (ACE) is produced by pulmonary endothelial cells (normal site) and by activated macrophages/epithelioid cells. In sarcoidosis, activated epithelioid macrophages (which form the characteristic non-caseating granulomas) produce excess ACE. Serum ACE is elevated in ~60% of active sarcoidosis cases and correlates with granuloma burden. It is also elevated in other granulomatous diseases (berylliosis, hypersensitivity pneumonitis, Gaucher disease, leprosy, miliary TB) — so it is not specific for sarcoidosis. ACE inhibitors are structurally designed to mimic the transition state of the ACE-catalyzed peptide hydrolysis reaction.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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