Which single complement fragment combines three actions relevant to acute inflammation: neutrophil chemotaxis, mast cell degranulation, and enhancement of neutrophil adhesion and oxidative burst?

• A C5a ✓
• B C3b
• C C4a
• D Membrane attack complex

Explanation

C5a is the most important complement-derived chemotactic agent for neutrophils and monocytes, is a potent anaphylatoxin causing mast cell degranulation with histamine release, and directly increases neutrophil integrin avidity and the respiratory burst. C3b serves mainly as an opsonin, C4a is a weak anaphylatoxin with little chemotactic activity, and the membrane attack complex kills gram-negative bacteria without acting as a chemoattractant.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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