What are Antibodies?
Antibodies, also known as immunoglobulins (Ig), are Y-shaped proteins produced by the immune system, specifically by B cells (plasma cells). Their primary function is to identify and neutralize foreign objects, such as bacteria, viruses, and other pathogens, in the body. They are a critical component of adaptive immunity.
How Antibodies Work: Specificity and Binding
Each antibody is highly specific, designed to recognize and bind to a unique molecular structure called an antigen, which is found on the surface of pathogens or toxins. The 'arms' of the Y-shape contain variable regions that fit precisely with a particular antigen, much like a lock and key. This binding marks the pathogen for destruction by other immune cells or directly neutralizes its ability to infect.
An Example: The Immune Response to a Virus
When your body encounters a virus, such as the flu virus, specific B cells recognize antigens on its surface. These B cells then multiply and transform into plasma cells, which mass-produce antibodies tailored to that virus. These antibodies circulate in your bloodstream, attaching to flu virus particles, preventing them from infecting healthy cells, and signaling other immune cells to clear them from the system.
Importance in Health and Medicine
Antibodies are fundamental to long-term immunity, as demonstrated by their role in vaccines, which stimulate antibody production without causing disease. They are also vital in diagnostic tests (e.g., pregnancy tests, COVID-19 antibody tests) and therapeutic treatments, such as monoclonal antibody therapies used to treat cancers, autoimmune diseases, and viral infections by targeting specific harmful cells or proteins.