Which of the following is not an activator of alternate complement system?: (A) Factor H, (B) IgA, (C) Bacteria, (D) Immune complex
Answer is D. Ans. (d) Immune complexAlternative pathway*. Triggered by microbial surface molecules (e.g., endotoxin, or LPS), complex polysaccharides, cobra venom, and other substances, in the absence of antibody*. IgA can directly activate this pathway