Benign prostate-specific antigen (BPSA) in serum is increased in benign prostate disease.
BACKGROUND
BPSA is a "benign" form of free prostate-specific antigen (PSA) that is increased in prostate transition zone tissues of men with pathologic benign prostatic hyperplasia (BPH). We developed an immunoassay to determine the concentration of BPSA in the serum of men with BPH.


METHODS
The BPSA antigen was purified by HPLC, and murine monoclonal antibodies were prepared by standard methods. A fluorogenic ELISA was developed with high specificity for BPSA and no cross-reactivity with other forms of PSA.


RESULTS
The BPSA immunoassay had a lower limit of detection of 6 ng/L and a cross-reactivity of <1% with all other clipped and nonclipped forms of PSA. The BPSA antibody was specific for the internal Lys(182) cleavage site that characterizes BPSA. Biopsy-negative men with a median total PSA of 4.8 micro g/L had a median of 0.22 micro g/L BPSA, representing 25% of the free PSA in serum. BPSA ranged from 0% to 60% of the free PSA in serum. BPSA in a cohort of cancer serum also comprised 25% of the free PSA. Control serum from women or men without increased PSA had nondetectable BPSA.


CONCLUSIONS
BPSA is a significant percentage of the free PSA in BPH serum but not in control serum. The presence of prostate cancer does not alter the relative proportions of BPSA in sera with <10 micro g/L PSA. BPSA has a wide distribution of concentrations in the serum and may provide clinical information for the study of men with BPH.
Linton
Harry J
HJ
Hybritech Incorporated, a subsidiary of Beckman Coulter, Inc., 7330 Carroll Road, San Diego, CA 92121, USA.
Marks
Leonard S
LS
Millar
Lisa S
LS
Knott
Christine L
CL
Rittenhouse
Harry G
HG
Mikolajczyk
Stephen D
SD
D000328:Adult; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D051379:Mice; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000175:diagnosis*; D011471:Prostatic Neoplasms / Q000175:diagnosis*
D017430:Prostate-Specific Antigen