What Is a Hapten?

Hapten (hapten), also known as incomplete antigen (referred to as incomplete antigen), refers to the inability to induce an immune response when it exists alone, that is, it does not have immunogenicity, but when it is related to large protein or non-antigenic polylysine Small molecules such as acids can be cross-linked or combined (usually in the form of covalent bonds) to obtain immunogenicity, thereby inducing an immune response. Because a hapten needs to bind to a response effector product to induce an immune response, it is only immunoreactive (antigenic) and not immunogenic. ^[1] Common haptens are polysaccharides, lipids, nucleic acids, and certain small molecule compounds and drugs. ^[2]

The concept of hapten was originally developed by Austrian biologist Karl Landsteiner in 20

Hapten antibiotics

-lactam antibiotics, especially penicillins, are more prone to allergic symptoms during use. The reason is that such drugs are prone to degradation during storage and produce substances such as penicillic acid. These substances are not immunogenic in themselves, but penicillium thiazolyl is an important antigenic determinant. ^[6] Once combined with serum proteins to form a complete antigen, it can induce an immune response in the body. The reaction produces a large number of IgE antibodies, which mediate type I hypersensitivity reactions, which are allergic to penicillin. ^[1] Because different types of penicillin can be degraded to produce the same penicillium thiazolyl group, a strong cross-allergic reaction can occur between penicillins. ^[6]

However, cephalosporin antibiotics have a lower incidence of allergic reactions due to the inability to form stable cephalosporins. At the same time, the different structural side chains generated by cephalosporin degradation are its main antigenic determinants, so no cross-allergic reaction will occur between different cephalosporins. ^[6]

Hapten Anesthetic

Halothane (trifluorobromochloroethane) was used as an anesthetic around the 1950s. It is metabolized into trifluoroacetyl chloride in the body and then reacts with proteins in the liver to form new antigens. After eliciting an immune response to this neoantigen, re-inhalation of halothane will activate the immune response and cause liver inflammation. ^[4]