This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Which subtype of IgG activates alternate complement system. \nSelect and explain. \nA. IgGl, B. IgG2, C. IgG3, D. IgG4', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. id 'd' i.e. IgG4 * Four subclasses oflgG are there with IgG{ is found in greatest amount and IgG4 in least amount.IgG,-65%IgG3-8%IgG2-23%IgG4-4%* Ig G1, Ig G3 and sometimes Ig G2 activate classical complement pathway.* Ig G4 activates alternate complement pathway.* IgG2 is directed against polysaccharide antigen so it is important in defence against encapsulated bacteria.", 'role': 'assistant'}]