IMMUNOCHEMICAL DETECTION OF 5-ALPHA-REDUCTASE IN HUMAN SERUM

This study represents a continuing effort to find a new biomarker for the diagnosis and management of prostatic cancer. Polyclonal antibodie s were prepared to a peptide (CAKP) representing amino acids 28 to 43 of the 5 alpha-reductase type 2 isozyme. Using immunoaffinity-purified antibodies, the sera of 62 patients were examined by Western blot fol lowing polyacrylamide gel electrophoresis. A positive band was detecte d in the sera of several patients at 42 kDa compatible with the purifi ed native glycosylated 5 alpha-reductase type 2. These bands were null ified on coincubation of the the antibody with the CAKP peptide. Analy sis by high-performance liquid chromatography and amino acid sequencin g by N-terminal Edman degradation of the immunoaffinity-purified antig en to the antipeptide antibodies of a patient with adenocarcinoma of t he the prostate suggests that the 5 alpha-reductase type 2 isozyme may be linked to an immunoglobulin. An identical immunoaffinity-purified antigen to the CAKP peptide was isolated from a section of prostatic t issue from a different patient showing benign prostatic hypertrophy wi th severe dysplasia. It is suggested that an immunological response to the 5 alpha-reductase type 2 isozyme was elicited in both instances. (C) 1996 by Elsevier Science Inc.