PROSTATE-SPECIFIC ANTIGEN AND ITS COMPLEXES WITH ALPHA(1)-ANTICHYMOTRYPSIN IN THE PLASMA OF PATIENTS WITH PROSTATIC DISEASE

Objective: To improve the specificity and sensitivity of the prostate- specific-antigen (PSA) assay for the distinction between prostate canc er and benign prostate hyperplasia (BPH). Methods: Two sensitive immun oassays, one that measures free PSA and PSA complexed to alpha(1)-anti chymotrypsin (alpha(1)-ACT) with the same efficiency (PSAag assay) and another that specifically measures the complex between PSA and alpha( 1)-ACT, have been designed to measure the PSA forms in the plasma of 8 4 patients with prostate disease and in the seminal plasma from 60 hea lthy individuals. Results: The proportion of plasma PSA in complex wit h alpha(1)-ACT was significantly higher in the 34 patients with prosta te cancer(89+/-12%, mean+/-SD; median, 91%) than in the 50 patients wi th BPH (71+/-12%; 73%) and did not correlate with the total amount of PSA. Normal seminal plasma (n=60) had 2.1+/-0.6 mg/ml PSA, 175+/-62 mu g/ml alpha(1)-ACT and 9.6+/-3.4 mu g/ml PSA:alpha(1)-ACT complex. Con clusion: These results confirm that PSA:alpha(1)-ACT may be a good mar ker for a differential diagnosis of carcinoma of the prostate and BPH.