Which single complement fragment combines both anaphylatoxin activity, causing mast cell degranulation, and chemotactic activity for neutrophils?
- A C3a
- B C5a ✓
- C C3b
- D C5b-9
Correct answer: B. C5a
Explanation
B5a is unique among complement fragments in being both a potent anaphylatoxin, triggering mast cell histamine release and smooth muscle contraction, and the most important chemotactic agent for neutrophils generated by complement activation. B3a is an anaphylatoxin but lacks significant chemotactic activity. B3b is the major opsonin, and B5b-9 is the membrane attack complex that lyses cells without chemotactic function.
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.