LAUSR

Haptens, which are small antigens such as peptides and drug compounds, are very weakly or nonimmunogenic by themselves and require the assistance of carrier proteins: complex molecules capable of eliciting a strong immune response in the host on injection. The haptens serve as epitopes for binding to the antibodies on the B-cell surface, and the carriers provide the MHC class II-T-cell receptor binding sites. Keyhole limpet hemocyanin (KLH) is one of the most widely used of such carrier proteins. KLH-hapten conjugates are commonly used in antibody generation in a variety of hosts such as mice, rats, and rabbits. Because KLH is harvested from mollusks, it is physiologically distant from mammalian species and less likely to produce antibodies that cross-react mammalian antigens. Maleimide activation of carrier proteins makes it possible to conjugate sulfhydryl-containing haptens, and hence this chemistry is widely used for conjugating KLH with haptens.