Immunoglobulins

Marked Ig, also called antibodies. These are the main proteins of the immune system. Immunoglobulins make up about 20% of blood plasma proteins. However, they are also found in extravascular fluid, mucous secretions, and in the membranes of certain lymphocytes. Immunoglobulins are synthesized and secreted by plasma cells, which are formed from B lymphocytes as they mature and differentiate after antigen stimulation. During the immune response, antibodies can be synthesized in lymph nodes, spleen, mucosal immune system, and bone marrow. The structural unit of immunoglobulin molecules is a Y-shaped monomer consisting of four polypeptide chains, two identical heavy chains, and two identical light chains linked together by disulfide bonds; furthermore, all chains differ in the amount of attached oligosaccharides. There are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM. Depending on the differing primary structure of heavy chains within the classes, the chains are marked a, d, e, g, and m; there are two types of light chains: k and l. Functionally, two parts of the immunoglobulin molecule can be distinguished: the antigen-binding (antigen-binding) and the effector. The Fab fragments recognize and bind antigens. The binding of antibodies to antigens is an important part of immune protection. This way, toxins can be neutralized, and, for example, surface antigens of viruses that the virus needs to enter the cell can be blocked.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė