This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunity, Subject name: Pathology
Which of the following are/is not an activator of alternate complement system? 
Select and explain. 
A. Factor H, B. IgA, C. Bacteria, D. Toxin
A: Factor H
Answer: A: Factor H 
Explanation: Ans. (a) Factor H(Ref: Robbins 9th/pg 162-164)The alternative pathway, can be triggered by microbial surface molecules (e.g., endotoxin, or LPS), complex polysaccharides, cobra venom, and other substances, in the absence of antibodyFactor I and H inhits complement activation