Antigénicité

Antigénicité refers to the ability of a substance to induce an immune response, specifically the production of antibodies. This substance, known as an antigen, is typically a molecule that the immune system recognizes as foreign. Antigens are often proteins or large polysaccharides found on the surface of pathogens like bacteria and viruses, or on transplanted tissues. The immune system's response to an antigen involves the activation of lymphocytes, such as B cells, which then differentiate into plasma cells that secrete antibodies. Antibodies are proteins that bind to specific antigens, marking them for destruction by other immune cells or neutralizing their harmful effects. The concept of antigénicité is crucial in immunology, vaccinology, and transfusion medicine. Vaccines, for example, are designed to introduce weakened or inactivated antigens to stimulate an immune response without causing disease, thereby conferring immunity. Similarly, understanding antigénicité is vital to prevent immune rejection of transplanted organs, where the antigens on the donor tissue are recognized as foreign by the recipient's immune system. The strength of the antigénic response can vary depending on factors such as the antigen's structure, its quantity, and the host's immune status.