Which complement fragment performs both anaphylactic (vasodilator) activity and neutrophil chemotactic activity?
- A C5a ✓
- B C3a
- C C3b
- D C4b
Correct answer: A. C5a
Explanation
A5a is the most potent anaphylatoxin and also a strong chemoattractant for neutrophils and monocytes through its receptor A5aR. A3a is anaphylactic but has little chemotactic activity, which is the fact that kills option B. A3b and its cleavage product iC3b are opsonins recognized by complement receptor 1 and complement receptor 3 respectively, and A4b likewise serves mainly as an opsonin rather than a chemotaxin.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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