<prompt> Which of the subclass of IgG has the maximum serum concentration?IgG1IgG2IgG3IgG4  <response>: IgG is the most abundant of the immunoglobulins. It has two heavy and two light chains linked by disulfide bonds. 4 subclasses of IgG are present, each differ from each other based on the amino acid sequence. Each of the 4 subclasses has unique epitopes. The subclasses of IgG are present in different amounts with IgG1IgG2IgG3IgG4. IgG1 subclass has the maximum serum concentration. Ref: Infection, Resistance and Immunity By Julius P. Kreie, 2nd Edition, Page 118 