A prostate antigen in sera of prostatic cancer patients.

A prostate antigen has been detected by a rocket immunoelectrophoresis technique in 17 of 219 sera obtained from patients with advanced prostatic cancer. Sera from 175 patients with nonprostatic cancers, including those with late-stage disease of the breast, lung, colon, rectum, stomach, and pancreas, were antigen negative as were 20 samples each from normal adults and age-matched males. Antigen in sera showed immunological identity with antigen in prostate tissue as determined by immunoprecipitation peak enhancement experiments. Using antibody affinity chromatography and radioimmunoprecipitation techniques, the antigen in sera was purified and subjected to sodium dodecyl sulfate electrophoresis; it exhibited a molecular weight of approximately 36,000, similar to that of antigen isolated from prostatic tissue.