Which complement component acts as a potent chemotactic factor for neutrophils?

Which complement component acts as a potent chemotactic factor for neutrophils?

• A. C3a
• B. C4a
• C. C5a
• D. C1q

Answer: (C)

During complement activation, C5 is split to form C5a and C5b. C5a is a powerful chemoattractant for neutrophils, drawing them to sites of infection and inflammation by binding to the C5a receptor on neutrophils. This interaction not only guides neutrophils toward the stimulus but also enhances their adherence, activates them, and promotes degranulation and the respiratory burst. C3a and C4a are also anaphylatoxins that promote inflammation, but they are much weaker at attracting neutrophils. C1q is part of the classical pathway’s initiation; it helps recognize immune complexes but does not function as a neutrophil chemoattractant. Therefore, C5a stands out as the most potent signal for neutrophil chemotaxis.

During complement activation, C5 is split to form C5a and C5b. C5a is a powerful chemoattractant for neutrophils, drawing them to sites of infection and inflammation by binding to the C5a receptor on neutrophils. This interaction not only guides neutrophils toward the stimulus but also enhances their adherence, activates them, and promotes degranulation and the respiratory burst.

C3a and C4a are also anaphylatoxins that promote inflammation, but they are much weaker at attracting neutrophils. C1q is part of the classical pathway’s initiation; it helps recognize immune complexes but does not function as a neutrophil chemoattractant. Therefore, C5a stands out as the most potent signal for neutrophil chemotaxis.