Which complement fragment serves as the most potent chemotactic agent for neutrophil recruitment during acute inflammation?

• A C5a ✓
• B C3a
• C C3b
• D C5b-9 (membrane attack complex)

Explanation

C5a is the most potent chemotactic complement fragment for neutrophils, monocytes, eosinophils, and basophils; it also stimulates degranulation, oxidative burst, and upregulates leukocyte adhesion molecules. C3a (and to a lesser extent C5a) act as anaphylatoxins causing mast cell degranulation and increased vascular permeability. C3b is the principal opsonin. The MAC (C5b-9) causes osmotic lysis of target cells and is not a chemotactic factor.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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