[Immunochemical studies of human cathepsin D]

Rabbit antiserum against human liver cathepsin D was raised. The antiserum did not cross-react with cathepsins D from tissues of other species (bovine liver, bovine spleen, chicken liver). The study of cathepsins D isolated from human pathologically altered tissues showed that cathepsins from kidney malignant tumor and from myeloleucosis-induced spleen tumor were immunologically identical to the enzyme from normal liver. Cathepsins from liposarcoma and uterine myoma were characterized by partial identity with the enzyme from normal liver. Cathepsins D isolated from various human livers exhibited individual quantitative differences in antigenic properties, a fact to be taken into account in development of an immunochemical method for identification of cathepsin D. The low immunogenicity of human cathepsin D for rabbits and inadequate suitability of these animals for raising appropriate antisera was also considered.