Question

What is the basic structure of an antibody? What are the antigen‐binding sites? What are the types of immunoglobins? How do antibody isotypes differ from antibody idiotypes? Describe the functions of each immunoglobins type.

Answer 1

Antibody is a Y shaped molecule consisting of four polypeptides ( two Heavy Chain and two light chain joined by disulfide bonds ) . The uppermost portion , designing of light and heavy chains, a variable reason consisting of amino acids is the binding site of antigen.

Antibodies are of five major types :

• IgM : the constitute 6% of the total percentage of antibody in serum. They have 10 antigen binding sites. They are the main antibody of primary responses that enhances the ingestion of cell by phagocytosis.
• IgG : they are the major type of antibodies that constitutes about 80% of total antibodies in serum. Its main function is in secondary response that neutralizes toxins and opsonization. This antibodies also provide long-term protection and protect against bacteria virus.
• IgA : the constitutes 13% of the total antibody present in serum. Tjey are the first defence that are secreted into mucus, saliva, tears and colostrum.
• IgE : they constitute least amount ( 0.002% ) their main function is in allergic and antiparasitic activities. They binds to mast cells and basophils of lymphocytes.
• IgD : constitute only 1% of total antibodies in serum. They are present on the surface of B cells induces antibody production.

Antibody isotypes : antibody are the tyleof antibodies present in serum based on the difference between heavy chain. They all have different functions as discussed above.

Antibody idiotype : based on variable region, antibodies that recognizes different specific epitopes are known as antibody idiotype.