Question

Most abundant immunoglobulin is
A. IgA
B. IgE
C. IgG
D. IgM

Answer 1

Hint: This immunoglobulin is the main type of antibody that is found in the blood and extracellular fluid and is involved in controlling different types of infections that occur in the body tissues.

Complete answer:
Considering the abundance of antibodies, IgG is the most abundant among the five and is about 75-80% of the total antibodies. Antibodies, also known as Immunoglobulins (Igs), are glycoproteins produced by specific white blood cells. In our body, there are five types of Immunoglobulins – IgG, IgA, IgM, IgD, and IgE. These molecules serve as a critical part of our immune system and specifically recognize and bind to the particular antigens to destroy or inactivate them. A diagram of IgG has been given below -

In each molecule of immunoglobulin, there are two pairs of polypeptide chains that are different in sizes. The smaller chains are called ‘light’ chains and are designated as L-chains while the larger ones are called ‘heavy’ chains and are designated as H-chains. In the structure of immunoglobulins, the light chain is attached to the heavy chain by a disulfide bond, and the two heavy chains are also joined together by disulfide bonds. The heavy chains are different for each class of the immunoglobulin and are designated by using Greek letters as IgG (Gamma), IgA (alpha), IgM (mu), IgD (delta), and IgE (epsilon). Unlike the heavy chains, the light chains are similar in all classes of immunoglobulins and they occur in two varieties as kappa (k) and lambda (l). In a molecule of immunoglobulin, either kappa or lambda chains can be present, but never both.

So, the correct answer is “IgG”.

Note: As per the abundancy, IgA follows IgG and consists of around 10-15% of the total amount of the antibodies found in our body. IgM is pentameric and makes up around 5-10% of the total while both IgD and IgE are found in very little amounts ranging somewhere between 0.001-0.002% each but are important as other antibodies.