What is the primary function of an antigen?

The primary function of an antigen is to induce an immune response. Antigens are substances that are recognized by the immune system as foreign, which stimulates a cascade of immunological events. When an antigen enters the body, it is detected by immune cells, particularly B cells and T cells. This recognition triggers the activation of these cells, leading to the production of antibodies by B cells or the activation of T cells that can directly kill infected cells or help other immune cells respond.

Through this process, the immune system learns to recognize and remember the specific structure of the antigen, allowing for a more rapid and effective response upon subsequent exposures. Thus, the role of an antigen is crucial in the initiation and shaping of the immune response, enabling the body to fight off infections and diseases.