Surface Antigen

A surface antigen is a molecule, typically a protein or carbohydrate, present on the exterior of cells, viruses, or other pathogens. These antigens serve as markers that can be recognized by the immune system and are critical for cell identification and immune response activation. Surface antigens are widely used in diagnostics and therapeutics due to their accessibility on cell surfaces. They function as identifiers for cells or pathogens and help the immune system distinguish between self and non-self entities. In infectious diseases, specific surface antigens indicate active presence, while blood group antigens are classic examples of surface markers that determine compatibility. Many cancer therapies target tumor-specific surface antigens to deliver drugs directly to malignant cells. Surface antigens may be proteins, carbohydrates, glycoproteins, or glycolipids. Their structure determines how they interact with antibodies and other components of the immune system. Detection often uses immunoassays.

Targeting for drug delivery; immune modulation.