Rapid, fully automated radioimmunoassay of prostatic acid phosphatase in serum

Prostatic acid phosphatase was purified from human semen and its purity established by biochemical and immunological criteria. Rabbits were injected with the purified isoenzyme to raise specific antisera. The prostatic acid phosphatase was radiolabeled with 125I by the Chloramine T method. We developed a fully automated double-antibody radiommunosassay for measuring prostatic acid phosphatase in serum from patients with carcinoma of the prostate and from several control groups. The lower detection limit of the radioimmunoassay was 2.0 microgram of prostatic acid phosphatase per litre of serum. Values for most members of the control group was <2.0 microgram/L; patients with metastatic carcinoma of the prostate had values ranging from <2.0 to 300 microgram/L of serum.