epitopejä

Epitopes, also known as antigenic determinants, are specific regions on the surface of an antigen that are recognized by the immune system, particularly by antibodies, B cell receptors, and T cell receptors. These sites are essentially the molecular "flags" that allow the immune system to identify foreign substances like bacteria, viruses, and other pathogens as targets for an immune response. An antigen, which is typically a larger molecule, can possess multiple different epitopes, and each epitope may elicit a distinct immune response. The shape and chemical composition of an epitope are crucial for its recognition. Antibodies, for instance, have binding sites that are complementary in three-dimensional structure to the epitope they target. T cell receptors, on the other hand, recognize epitopes presented by major histocompatibility complex (MHC) molecules on the surface of other cells. Understanding epitopes is fundamental to fields such as immunology, vaccinology, and diagnostics, as it allows for the design of targeted therapies and diagnostic tools. For example, vaccines often contain specific epitopes from pathogens to prime the immune system without causing disease.