hapten

hapten, small molecule that stimulates the production of antibody molecules only when conjugated to a larger molecule, called a carrier molecule. The term hapten is derived from the Greek haptein, meaning “to fasten.” Haptens can become tightly fastened to a carrier molecule, most often a protein, by a covalent bond. The hapten-carrier complex stimulates the production of antibodies, which the unbound hapten cannot do, and becomes immunogenic (capable of eliciting an immune response). The hapten...