A 32-year-old HIV-positive man on no medications has a CD4 count of 180 cells/μL. Which complement pathway is classically activated by mannose-binding lectin (MBL) on the surface of microorganisms?
- A Classical pathway
- B Alternative pathway
- C Lectin (MBL) pathway ✓
- D Terminal lytic pathway only
Correct answer: C. Lectin (MBL) pathway
Explanation
Mannose-binding lectin (MBL) binds carbohydrate patterns on microbial surfaces and activates the lectin pathway (also called MBL pathway) of complement by recruiting MBL-associated serine proteases (MASPs) which cleave C4 and C2. The classical pathway is initiated by antibody-antigen complexes, and the alternative pathway is activated by direct microbial surface components without antibody. The terminal lytic pathway (MAC) is the final common pathway of all three routes.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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