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': 'The serum concentration of which of the following human IgG subclass is maximum ? \nSelect and explain. \nA. IgG 1, B. IgG 2, C. IgG 3, D. IgG 4', 'role': 'user'}, {'content': "Answer: A \nExplanation: IgG has four subclasses: IgG1, IgG2, IgG3 and IgG4 due to the presence of gamma1, gamma2, gamma3 or gamma4 H chains. - the subclasses differ from one another in the size of the hinge region and the number and position of the interchain disulfide bonds between the heavy chains. - IgG1 is distributed in human serum in the approximate propoion of 65%, IgG2 in 23%, IgG3 in 8% and IgG4 in 4 %. Reference:Anathanarayan & paniker's 9th edition, pg no: 97 <\\p>", 'role': 'assistant'}]