antigeinien

An antigen is a molecule or molecular structure capable of inducing an immune response in the body, specifically the production of antibodies or activation of immune cells. Antigens are typically large, complex molecules, often proteins or polysaccharides, that originate from pathogens such as bacteria, viruses, fungi, or parasites. They can also be derived from non-infectious sources, including toxins, pollen, or foreign tissues.

The immune system recognizes antigens as foreign or harmful, triggering an adaptive immune response. This involves the activation of B cells, which produce antibodies specific to the antigen, and T cells, which help coordinate the response or directly destroy infected cells. The binding of an antigen to an antibody or immune receptor is highly specific, resembling a lock-and-key mechanism, which allows the immune system to target pathogens precisely.

Antigens play a crucial role in vaccination, where weakened or inactivated pathogens are introduced to the body to stimulate an immune response without causing disease. This primes the immune system to recognize and respond more effectively to future encounters with the actual pathogen. Antigens are also essential in diagnostic tests, such as enzyme-linked immunosorbent assays (ELISAs), where their presence or absence can indicate infection or immune activity.

Some antigens are self-antigens, meaning they belong to the body’s own cells, while others are non-self (foreign) antigens. Autoimmune diseases occur when the immune system mistakenly targets self-antigens, leading to inflammation and tissue damage. Understanding antigen structure and function is fundamental in immunology, medicine, and biotechnology, particularly in the development of vaccines, therapies, and diagnostic tools.