In the Arthus reaction (Type III hypersensitivity), which complement components are MOST critically responsible for neutrophil recruitment and subsequent tissue damage at the site of immune complex deposition?
- A C3b and C4b
- B C1q and C1r
- C C5a and C3a ✓
- D C6, C7, C8, and C9 (MAC)
Correct answer: C. C5a and C3a
Explanation
In the Arthus reaction, locally deposited immune complexes activate complement via the classical pathway. C5a (most potent) and C3a are anaphylatoxins that act as chemotactic factors for neutrophils, increase vascular permeability, and promote mast cell degranulation, driving the intense local inflammatory response. C3b and C4b act as opsonins. The MAC (C5b-9) causes lysis of cellular targets but is less relevant to the neutrophil-mediated tissue damage in Arthus.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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