Question

How are antibodies unique? Please discuss the structure of an antibody. What are the V and C regions? Discuss how the few hundred genes involved are capable of making endless amounts of antibodies. Besides medical treatment what is another way antibodies can be used?

Answer 1

Ans. Antibodies are proteins that are produced by the higher organism's immune system to help protect the host against invasion by pathogens. When the external substance like a virus, bacteria, toxins, etc. challenges the host, the initial reaction of certain host immune cells known as a macrophage is to absorb and biochemically process these invaders. This biochemical processing basically produces a blueprint used to build an immune reaction leading to antibody formation. The unique characteristic of antibodies produced by an antigen is that they are synthesized to be highly specific for that antigen. Thus they can only chemically interact, bind, neutralize, and/or help in the destruction and removal of this particular antigen.

Each antibody comprises four polypeptides two heavy chains together with two light chains forming a molecule which is "Y" shaped. The sequence of amino acids in the tips of the "Y" differs significantly between various antibodies. Composed of 110-130 amino acids, this variable region provides the antibody with its specific binding antigen characteristics. The ends of the light and heavy chains form the variable region of the antibody. The constant region decides the antigen degradation mechanism. Antibodies, based on their constant area structures and immune function, are classified into five major groups, IgM, IgG, IgA, IgD, and IgE. The antibody amino-terminal variable or the V domains (VH and VL) of heavy and light chains make up the V region or the variable region of the antibody which allows the antibody to bind a specific antigen. While the C -region also called the constant region of the antibody forms the C-domain which consists of heavy and light chain domains (CH and CL) which help to determine the class of the antibody. The class of the antibody determines the functional property of the antibody.

The above image shows the basic structure of an antibody with its heavy and light chain along with constant and variable regions.

The above picture shows different types of antibodies produced by the human immune system.

IgM, IgG, IgA, IgD, and IgE are five big heavy chain groups. Such groups vary in their positions in our bodies and their way of promoting antigen removal in the innate system. By re-organizing DNA segments during B cell development before an antigen exposure, the immune system builds up billions of different antibodies with a small number of genes. Increased genetically modified antibodies can also be caused by mutation.

Beside medical treatment antibody have many different use like they are widely used for research purpose like flow cytometer, in-vivo applications of immunological studies, various immunological assays, immunosorbent assays, immunohistochemistry / immunocytochemistry, western blotting and many such biomedical research.