Vastaainojen

Vastaainojen, commonly written as vasta-aineet (antibodies), are proteins produced primarily by plasma cells that differentiate from B lymphocytes. They are a central component of the adaptive immune system and recognize specific antigens, such as proteins on pathogens, toxins, or abnormal cells. By binding to these targets, vastaainojen can neutralize threats directly or recruit other parts of the immune system to destroy or remove the invader.

Vastaainojen have a characteristic Y-shaped structure formed by two heavy chains and two light chains. The antigen-binding sites are located at the tips of the Y and are highly variable, allowing a vast diversity of specificity. Diversity arises through gene rearrangements (V(D)J recombination), junctional diversity, and somatic hypermutation. Vastaainojen are classified into isotypes or classes, including IgG, IgA, IgM, IgD, and IgE, each with distinct distribution and effector functions such as neutralization, opsonization, complement activation, or mucosal defense.

Production and immune response: Naive B cells recognizing an antigen activate and proliferate, differentiating into plasma cells that secrete large amounts of vastaainojen and into memory B cells for faster responses upon re-exposure. Affinity maturation improves binding strength over time, and class switching modifies the antibody class without changing antigen specificity.

Applications: Vastaainojen are central to medical diagnostics and therapeutics. They are used in immunoassays, imaging, and rapid tests, and as monoclonal antibodies to treat cancers, autoimmune diseases, and infectious diseases. Production methods include hybridoma technology, phage display, and recombinant expression, enabling both research and clinical use.