Hapten

Hapten (Greek hapto – to grab) – a part of a molecule of biopolymer or the chemical compound which are artificially synthesized and capable to react specific interaction with homologous antibodies, but not leading to antibody formation at introduction to an organism, unlike full-fledged antigens.

 
Whether you know that:

The most rare disease – a disease the Kura. Only representatives of the tribe Faure in New Guinea are ill it. The patient dies of laughter. It is considered that eating of a human brain is an origin of a disease.