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
Which immunoglobulin is scarce in human serum- 
Select and explain. 
A. IgA, B. IgG, C. IgM, D. IgE
D: IgE
Answer: D: IgE 
Explanation: IgE is an 8 S molecule. - resemble IgG structurally. - heat liable - affinity for the surface of tissue cells of the same species. - normal serum contains only traces of IgE ( a few nanograms per ml ) - greatly elevated levels in atopic conditions like asthma, hay fever. REF:Anathanarayan & paniker's 9th edition, pg no: 98,98 <\p>