The Most Common Circulating Antibody, Comprising About 80% of the Serum

Question

The most common circulating antibody, comprising about 80% of the serum immunoglobin, is
A) IgA.
B) IgC.
C) IgD.
D) IgG.

Accepted Answer

IgG is the most common circulating antibody, comprising about 80% of the serum immunoglobin. It is also the only antibody that can cross the placenta from mother to fetus, providing passive immunity to the newborn. IgA, IgC, and IgD are all less common circulating antibodies.