ABSTRACT
The term ‘antigen’ refers to any entity, whether a cell, a macromolecular assembly or a single molecule, which can elicit an immune response in a competent, vertebrate host and be recognized specifically by the products of that immune response. The ability of antigens to react specifically with complementary antibodies is known as ‘antigenic reactivity’ or ‘antigenicity’, while their capacity to generate an immune response is called ‘immunogenicity’. It should be noted that immunogenicity is not an intrinsic property of the antigen but a relational property that depends on the gene repertoire and regulatory mechanisms of the host being immunized and which has no meaning outside the context of the host (Berzofsky 1985). For instance, mouse serum albumin is an antigenic protein that is immunogenic in the rabbit but not normally in the mouse because of the regulatory mechanism known as immunological tolerance.
