A 30-year-old woman with SLE has anti-dsDNA and anti-Sm antibodies. The mechanism of lupus nephritis involves deposition of immune complexes, activating complement. The complement fragment directly responsible for recruiting neutrophils and monocytes is:
- A C3b
- B C5a ✓
- C C4b
- D C1q
Correct answer: B. C5a
Explanation
C5a is the most potent chemotactic factor generated during complement activation; it recruits neutrophils and monocytes to the site of immune complex deposition and also directly activates these cells. C3b is an opsonin that promotes phagocytosis; C4b also participates in opsonization and immune complex clearance; C1q initiates the classical pathway when bound to immune complexes.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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