Which of the subclass of IgG has the maximum serum concentration?: (A) IgG1, (B) IgG2, (C) IgG3, (D) IgG4
Answer is A. 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 IgG1>IgG2>IgG3>IgG4. IgG1 subclass has the maximum serum concentration. Ref: Infection, Resistance and Immunity By Julius P. Kreie, 2nd Edition, Page 118