Immunological comparison between prostate-specific antigen and gamma-seminoprotein.

Prostate-specific antigen (PA) and gamma-seminoprotein (gamma-Sm) were compared by immunocytochemical, immunodiffusion and immunoblotting methods using rabbit anti-PA antibody and rabbit anti-gamma-Sm antibody. Enzyme immunoassays (EIAs) were developed for measurements of PA and gamma-Sm to determine a correlation between serum PA and gamma-Sm levels in patients with prostate cancer. The patterns of localization and distribution of PA and gamma-Sm were identical in prostate tissue sections, including benign and cancerous human prostates. The immunodiffusion study showed that the antigens with which anti-PA antibody and anti-gamma-Sm antibody reacted in seminal plasma and prostate tissue homogenates were identical to each other. In the immunoblotting study, anti-PA antibody and anti-gamma-Sm antibody recognized a single antigen corresponding to a molecular weight of approximately 33,000 both in seminal plasma and prostate tissue homogenates. The EIAs developed in this study were sensitive, specific, and reproducible, and the correlation between serum PA and gamma-Sm values determined by these EIAs was highly significant (r = 0.99, P less than 0.001). These results indicated that PA and gamma-Sm were immunologically identical and that serum PA and gamma-Sm determined by immunoassays using anti-PA antibody and anti-gamma-Sm antibody should be evaluated as identical tumor markers for serodiagnosis of prostate cancer.