Which complement anaphylatoxin is the most potent direct trigger of mast cell degranulation and also the most powerful chemotactic agent for neutrophils?

• A C3b
• B C4b
• C C1q
• D C5a ✓

Explanation

C5a (anaphylatoxin) is the most potent complement-derived mediator: it directly triggers mast cell degranulation releasing histamine and leukotrienes, causes smooth muscle contraction, and is the most powerful chemotactic agent for neutrophils and monocytes. C3a is also an anaphylatoxin but less potent than C5a. C3b and C4b are primarily opsonins; C1q initiates the classical pathway activation.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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