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Question
Which is the first antibody to be produced in primary response to an antigen?
Which is the first antibody to be produced in primary response to an antigen?
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Solution
The correct option is A IgM
Immunoglobulins, also known as 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 immune response).
Five different classes of antibodies are produced in the body, namely, IgA, IgG, IgE, IgM and IgD.
A single antibody molecule is represented as H2L2 (made up of two long heavy (H) chains and two short light (L) chains joined to each other by disulfide bonds) and has two antigen binding sites normally.
In its secreted form, IgM is a pentamer composed of five four-chain units, and thus has 10 antigen-binding sites. IgM is the first antibody to be produced during the primary immune response followed by IgA on mucosal surfaces or IgG in the serum. IgM is present in lesser amounts in the body and is the largest of the five types of immunoglobulins.
IgA is known as the secretory immunoglobulin and is found in the secretions of the body including the colostrum. It acts as a first line of defence against invading microbes in body fluids.
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.
Hence, IgA and IgG are not the first antibodies to be produced as a result of primary immune response against an antigen.
Immunoglobulins, also known as 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 immune response).
Five different classes of antibodies are produced in the body, namely, IgA, IgG, IgE, IgM and IgD.
A single antibody molecule is represented as H2L2 (made up of two long heavy (H) chains and two short light (L) chains joined to each other by disulfide bonds) and has two antigen binding sites normally.
In its secreted form, IgM is a pentamer composed of five four-chain units, and thus has 10 antigen-binding sites. IgM is the first antibody to be produced during the primary immune response followed by IgA on mucosal surfaces or IgG in the serum. IgM is present in lesser amounts in the body and is the largest of the five types of immunoglobulins.
IgA is known as the secretory immunoglobulin and is found in the secretions of the body including the colostrum. It acts as a first line of defence against invading microbes in body fluids.
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.
Hence, IgA and IgG are not the first antibodies to be produced as a result of primary immune response against an antigen.
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