The Arthus reaction is an example of Type III hypersensitivity. The complement split product that is MOST responsible for neutrophil chemotaxis to the site of immune complex deposition is:
- A C3b
- B C4a
- C C5a ✓
- D C3a
Correct answer: C. C5a
Explanation
C5a is the most potent chemotactic complement fragment, attracting neutrophils to sites of immune complex deposition; it also acts as an anaphylatoxin causing mast cell degranulation. C3b is an opsonin that facilitates phagocytosis. C3a and C4a are anaphylatoxins causing smooth muscle contraction and mast cell degranulation but are weak chemoattractants compared to C5a. In Arthus reaction, IC deposition in vessel walls activates complement, and C5a recruits neutrophils causing vasculitis.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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