Antibody- Definition, Structure, Properties, Types, Classes, Applications


Antibodies are proteins that are produced by the immune system to identify and neutralize foreign substances, such as bacteria, viruses, or toxins, that enter the body . They have a Y-shaped structure with two tips that can bind to specific parts of the foreign substance, called antigens . By binding to antigens, antibodies mark them for destruction by other immune cells or mechanisms . Antibodies are made by a type of white blood cell called B cell, which divides and matures into a clone of identical cells when it encounters an antigen. Antibodies are a protective and essential part of the immune response, while antigens can cause disease or allergic reactions .

Another word for antibody is immunoglobulin (Ig), which is an abbreviation of the term "immune globulin". Immunoglobulins are classified into five major classes according to their structure and function: IgG, IgM, IgA, IgD, and IgE . Each class of immunoglobulin has a different role in the immune system and can be found in different locations in the body. For example, IgG is the most abundant and versatile immunoglobulin, which can cross the placenta and provide passive immunity to the fetus . IgM is the first immunoglobulin to appear in response to an initial exposure to an antigen and can activate the complement system . IgA is the main immunoglobulin found in mucosal secretions, such as saliva, tears, and breast milk, and protects against ingested and inhaled pathogens . IgD is mainly found on the surface of B cells and helps in their activation and maturation . IgE is involved in allergic reactions and parasitic infections and binds to mast cells and basophils .

Antibodies are important tools for medical diagnosis, treatment, and research. They can be used to detect the presence of specific antigens or antibodies in blood samples or other biological fluids. They can also be used to treat various diseases by providing passive immunity or by targeting specific antigens on cancer cells or pathogens. Moreover, they can be used to study the structure and function of different antigens and their interactions with the immune system. Monoclonal antibodies are a type of antibodies that are produced in a laboratory by cloning a single B cell that recognizes a specific antigen. Monoclonal antibodies have high specificity and affinity for their target antigen and can be used for various therapeutic and diagnostic purposes .

In summary, antibodies are proteins that recognize and bind to antigens and trigger their elimination from the body. They are produced by B cells as a result of interaction with antigens. They belong to different classes that have different structures and functions. They are also useful for medical applications as they can detect, treat, or study various antigens.