We compared our radioimmunoassay with the standard enzyme assay for prostatic acid phosphatase in the diagnosis of prostatic cancer. Serum samples from 50 controls, 113 patients with prostatic cancer, 36 with benign prostatic hyperplasia, 83 with other cancers, 20 with gastrointestinal disorders and 28 with total prostatectomies were randomized and studied by radioimmunoassay and enzyme assay. When the upper limit was set at 8.0 ng per milliliter (mean + 4 S.D.) the radioimmunoassay diagnosed prostatic cancer in 33, 79, 71 and 92 per cent of the patients with Stage I, II, III and IV disease. In contrast, the enzyme assay detected elevations of enzyme in the serum of 12, 15, 29, and 60 per cent respectively. No false-positive results were detected by either assay in normal controls but the radioimmunoassay test was positive in two patients with benign prostatic hyperplasia, in one patient after total prostatectomy, in nine with other cancers and in one of the group with gastrointestinal disorders. In contrast to the enzyme assay, the radioimmunoassay distinguished over half the cases of intracapsular prostatic cancer.

Detection of prostatic cancer by solid-phase radioimmunoassay of serum prostatic acid phosphatase

AN editorial in the Journal 1 brought widespread attention to a possible new role for serum acid phosphatase determinations in the detection of prostatic cancer. Citing data from an accompanying ar...

The predictive value of prostatic acid phosphatase as a screening test for prostatic cancer.

Prostatic Acid Phosphatase: Its Current Clinical Status

Gene expression and prostate specificity of human prostatic acid phosphatase (PAP): evaluation by RNA blot analyses.

Biological markers in prostate cancer.

We compared results of measurement of prostatic acid phosphatase activity in serum and various tissues by enzymatic assay and radioimmunoassay. By enzymatic assay, activity in serum is lost rapidly, even at room temperature. In contrast, there was no change in antigenic activity during 48 h by radioimmunoassay. The radioimmunoassay was more specific in 12 tissues and in serum than were several enzymatic assays that make use of inhibitors of the enzyme. The enzymatic assay resulted in 26.6% (24/90) false positives from non-prostatic cancer patients. In contrast, with radioimmunoassay there were only 5.5% (5/90) false positives. We conclude that immunological detection of prostatic acid phosphatase is the more reliable technique.

Comparison of human prostatic acid phosphatase by measurement of enzymatic activity and by radioimmunoassay.

Radioimmunochemical Measurement of Bone Marrow Prostatic Acid Phosphatase

We evaluated counterimmunoelectrophoresis for use in measuring prostatic acid phosphatase in detection of prostatic cancer. After staining for acid phosphatase, we could detect as little as 0.3 ng of purified enzyme standard complexed with antibody by this technique. However, when serum samples were used as antigen, the method was less sensitive (1.5-2.0 ng) because some of the serum proteins migrate with the phosphatase and decrease the intensity of the stain for acid phosphatase. For this reason we could not detect the phosphatase in serum samples of normal persons; only patients with moderately (or greater) increased activity in their serum showed positive results. In contrast, by radioimmunoassay as little as 1.0 ng of the phosphatase can be detected in serum.

Counterimmunoelectrophoresis in determination of prostatic acid phosphatase in human serum.

The effect of antibody on human prostatic acid phosphatase activity—I: Temperature and pH stabilization of acid phosphatase enzyme activity by rabbit antibody to acid phosphatase

Prostatic acid phosphatase may well be a prime antigenic protein in prostatic tissue and fluid. Extraction of the enzyme in highly purified form from prostatic fluid and benign hypertrophic prostatic tissue provides a unique antigen capable of inducing a prompt and specific antibody response in the goat and rabbit as manifested by immunodiffusion, immunoelectrophoresis, and immuno-fluoresence techniques. In prostatic cancer patients with elevated serum acid phosphatase levels it is possible to detect humoral circulating PAP antigen by standard immunoelectrophoretic methods and to confirm the existence of the enzyme by radioautography, L-tartrate inhibition, and the Gomori or Burstone staining procedures. Preliminary indirect prostatic immunofluorescence studies consistently demonstrated characteristic fluorescent foci in the paranuclear areas of benign prostatic epithelial cells, the presumed area of synthesis of prostatic acid phosphatase. Consideration has been given to the possibility of the development of a radioimmunoassay for prostatic acid phosphatase utilizing a heterologous antiserum to the enzyme extracted from human prostatic fluid.

Andras G. Foti

Papers

Comparison of human prostatic acid phosphatase by measurement of enzymatic activity and by radioimmunoassay.

Radioimmunochemical Measurement of Bone Marrow Prostatic Acid Phosphatase

Counterimmunoelectrophoresis in determination of prostatic acid phosphatase in human serum.

The effect of antibody on human prostatic acid phosphatase activity—I: Temperature and pH stabilization of acid phosphatase enzyme activity by rabbit antibody to acid phosphatase

Production of specific antibody to purified prostatic acid phosphatase.