The serum concentration of which of the following human IgG subclass is maximum?: (A) IgG1, (B) IgG2, (C) IgG3, (D) IgG4
Answer is A. IgG comprises about 75 to 85% of total serum immunoglobulinThe four IgG subclasses are numbered in order of their level in serumIgG1 is found in greatest amounts and IgG4 the least (Ref: Harrison's 18/e p2036)