Immunochemical properties of alpha-fetoprotein (AFP) and antibodies to autologous AFP.

Alpha-fetoprotein (AFP) is a strong immunogen when injected into another species, but does not elicit an immune response in the species of origin of the AFP. AFPs from different mammalian species are crossreactive. AFP and albumin show sequence homology. They do not crossreact in their native state, but their unfolded (reduced and carboxamidomethylated) forms are immunologically crossreactive. Antibodies to autologous AFP can be induced in animals by immunization with heterologous or modified homologous AFP. These antibodies eliminate the AFP normally measurable in the serum and delay the elevation of serum AFP caused by hepatomas, but do not protect against such tumors.