In the pathogenesis of atherosclerosis, oxidised LDL (oxLDL) entering the intima is taken up by macrophages via which non-regulated scavenger receptor, leading to foam cell formation?

• A LDL receptor (LDLR), a regulated receptor that undergoes downregulation
• B FcgammaRIII (CD16), an immunoglobulin Fc receptor activating ADCC
• C VLDL receptor, present on muscle and adipose tissue
• D Scavenger receptor A (SRA/CD204) and CD36, non-downregulated receptors on macrophages ✓

Explanation

Macrophages in the arterial intima take up oxidised LDL via scavenger receptors (principally SRA/CD204 and CD36), which unlike the classical LDLR are not downregulated by intracellular cholesterol accumulation. This unregulated uptake leads to massive cholesterol ester accumulation, converting macrophages into foam cells — the hallmark of the fatty streak and early atherosclerotic lesion. LDLR is regulated and its downregulation would actually reduce, not increase, cholesterol uptake. FcgammaRIII mediates antibody-dependent cellular cytotoxicity; VLDL receptor is found on adipose and muscle, not macrophages.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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