Human prostatic acid phosphatases: II. A double--antibody radioimmunoassay.

A double-antibody radioimmunoassay method for prostate-specific acid phosphatase (PAP) is presented. Experimental details are outlined to assess the reproducibility and reliability of the method under assay conditions. The upper limit of the serum PAP levels in the present assay was set at 2.4 ng/100 microliter by 162 determinations of normal serum samples. The serum PAP levels of patients with nonprostatic malignant tumors fell in the normal range, whereas the levels higher than 4.0 ng/100 microliter were found in patients with prostatic carcinoma.