Question

The immunoglobulin abundantly present in colostrum is

• A. IgG
• B. IgM
• C. IgE
• D. IgA

Answer 1

The correct option is D IgA

Immunoglobulins or antibodies are proteins, produced by B-lymphocytes, that are present in the body fluids to provide immunity against specific antigens (foreign substances that can trigger production of antibodies and immunological cells).

Five different classes of antibodies are produced in the body, namely, IgA, IgG, IgM, IgE and IgD. Of these, IgA is considered as the secretory antibody as it is found in all the secretions such as saliva, tears and mother’s milk.

The milk produced during the initial few days of lactation is called colostrum. It is a yellowish material which has high protein content. It contains the IgA antibody of the mother and is capable of providing passive immunity to the newborn who is prone to infections. Thus feeding colostrum to the child is of great significance, it prevents the establishment of microorganisms in the child’s intestine.

Figure : Action of IgA (SIgA) in intestine of newborn

IgE is mainly found in the mucous membranes, skin and lungs. It triggers allergic responses on contact with antigens.

IgM is the largest of the five classes of antibodies but is found in small amounts in the body. It is the first antibody to be produced in response to the antigen that has entered the body.

IgG is the only maternal immunoglobulin that can cross the placenta and provide natural passive immunity (immunity acquired by receiving antibodies from an immune individual) to the foetus.