An
epitope, also known as
antigenic determinant, is the part of an
antigen that is recognized by the
immune system, specifically by
antibodies,
B cells, or
T cells. For example, the epitope is the specific piece of the antigen that an antibody binds to. The part of an antibody that binds to the epitope is called a
paratope. Although epitopes are usually non-self proteins, sequences derived from the host that can be recognized (as in the case of autoimmune diseases) are also epitopes.