🏥 USMLE Exam Prep

Lipopolysaccharide (LPS) is a component of:

A Gram-positive cell wall
B The outer membrane of gram-negative bacteria, acting as an endotoxin
C Viral capsid
D Fungal cell wall

✓ Correct Answer: Option B

LPS: component of gram-negative outer membrane (Lipid A = toxic moiety). Activates TLR4 → macrophage/monocyte activation → TNF-α, IL-1, IL-6 release. Causes septic shock in high concentrations.

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