Which complement fragment serves both as an anaphylatoxin that degranulates mast cells and as the principal chemoattractant for neutrophils generated by the complement cascade?
- A C3b
- B C5a ✓
- C C4b
- D Factor B
Correct answer: B. C5a
Explanation
C5a is the most potent complement-derived anaphylatoxin, triggering histamine release from mast cells, and it is also a powerful neutrophil chemoattractant that upregulates integrins. C3a is anaphylatoxic but far weaker as a chemoattractant. C3b and C4b are opsonins, and Factor B is an alternative pathway protein without either activity, making these distractors functionally distinct.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.