Immunoglobulins, also known as antibodies, are Y-shaped glycoprotein molecules produced primarily by plasma cells, a type of white blood cell. They are a crucial part of the immune system, designed to specifically recognize and bind to antigens-foreign substances such as bacteria, viruses, or toxins-and help neutralize or eliminate them
. There are five main classes of immunoglobulins, each with distinct roles and locations in the body:
- IgG: The most abundant antibody in blood and tissue fluids, providing long-lasting immunity and capable of crossing the placenta to protect the fetus
- IgA: Found mainly in mucous membranes such as those in the respiratory, digestive, and urinary tracts, as well as in saliva, tears, and sweat; it protects body surfaces and acts as an anti-inflammatory agent
- IgM: The first antibody produced in response to a new infection, providing rapid defense
- IgE: Involved in protection against parasites and responsible for allergic reactions by triggering histamine release from certain white blood cells
- IgD: Its function is less well understood but is believed to play a role as a receptor on immature B cells
Immunoglobulins exist in two forms: soluble (circulating antibodies) and membrane-bound (B cell receptors). The membrane-bound form helps B cells recognize antigens and initiate antibody production
. In summary, immunoglobulins are specialized proteins that identify and neutralize pathogens, playing a vital role in immune defense and maintaining health
