Antibody structure render

Antibodies are Y-shaped glycoproteins produced by B lymphocytes that recognize and neutralize pathogens in the human immune system.

About this subject

Antibodies, also known as immunoglobulins, are essential proteins in the body's defense against infections. Structurally, they have a Y shape, with two Fab regions (fragment antigen-binding) at the tips and one Fc region (fragment crystallizable) at the base. This architecture allows each antibody to specifically bind to an antigen, such as viral or bacterial proteins, triggering immune responses including direct neutralization, opsonization, and complement activation. There are five major classes of immunoglobulins: IgG, IgM, IgA, IgE, and IgD, each with distinct functions and tissue distributions. IgG, for instance, is the most abundant in blood and can cross the placenta, providing passive immunity to the fetus. Antibody production is stimulated by vaccines, which expose the immune system to harmless antigens, generating immunological memory. This ability to recognize a vast array of antigens arises from genetic recombination of immunoglobulin genes, a process that generates millions of different specificities from a limited number of gene segments. Advances in molecular biology have enabled the creation of monoclonal antibodies, widely used in diagnostics, cancer therapies, and autoimmune disease treatments. The study of antibody structure, initiated with X-ray crystallography techniques, revolutionized understanding of the immune system and the development of biologic drugs.

Frequently Asked Questions

What is the difference between an antibody and an antigen?

Antibodies are proteins produced by the immune system that recognize and bind to foreign molecules called antigens. Antigens can be parts of viruses, bacteria, or other substances that trigger an immune response.

How are antibodies produced in the body?

Antibodies are synthesized by B lymphocytes, a type of white blood cell. When an antigen is detected, B lymphocytes differentiate into plasma cells that secrete large amounts of specific antibodies against that antigen.

What are monoclonal antibodies and what are they used for?

Monoclonal antibodies are identical antibodies produced in the lab from a single B lymphocyte clone. They are used in cancer therapies, autoimmune diseases, and infections, as well as diagnostics such as pregnancy tests and disease detection.