Human prostatic acid phosphatases: III. Counterimmunoelectrophoresis for rapid identification.

When serial dilution of standard prostatic acid phosphatases (PAP) was reacted with constant amounts of anti-PAP serum by counterimmunoelectrophoresis (CIEP), the detection end point of enzyme concentration was 0.25 ng in a 10 microliter sample volume. The PAP concentrations in unknowns can be quantitated by comparing the dilution end points of reference PAP with the testing samples. Serum PAP levels were determined by a radioimmunoassay (RIA) and CIEP using normal male and female sera and serum samples from patients with prostatic cancer and nonprostatic tumors. An excellent correlation was observed between the two assay results. According to RIA data, the concentration of PAP higher than 0.4 ng per 10 microliter (or 4.0 ng per 100 microliter) signify the elevation of serum or bone marrow PAP level beyond normal range (normal value 1.6 +/- 0.8 ng/100 microliter). Thus, the CIEP assay will be a simple and reliable screening method for the serum PAP levels in the clinical diagnosis of prostatic cancer.