What is an epitope?

An epitope is indeed defined as a small segment of an antigen. This term refers specifically to the part of the antigen that is recognized by the immune system, particularly by antibodies, T cells, and other immune receptors. Epitopes can be linear (sequential) or conformational (three-dimensional structures). The ability of the immune system to detect these specific regions is crucial for mounting an appropriate immune response against pathogens. Understanding epitopes is fundamental in fields such as vaccine development and immunotherapy, as targeted recognition can enhance the effectiveness of treatments.

In this context, while antibodies are important components of the immune response and are associated with the recognition of epitopes, they themselves are not epitopes but rather the products that bind to them. Similarly, T cells play a vital role in the immune response but are not the epitopes they recognize. A molecule that suppresses immune response does not align with the concept of an epitope, which is fundamentally about activation and recognition within the immune system.