CROSS-REACTIVITY OF 10 ANTI-PROSTATE-SPECIFIC ANTIGEN MONOCLONAL-ANTIBODIES WITH HUMAN GLANDULAR KALLIKREIN

Objectives, Prostate-specific antigen (PSA) is commonly used as a mark er for prostate disease. Prostate epithelium expresses both PSA and hu man glandular kallikrein (hK2) proteins, which share 80% sequence homo logy. The immunologic cross-reactivity of these two proteins could pot entially interfere with determination of PSA levels in diagnoses of pr ostate cancer. We set out to determine the extent of this crossreactiv ity for a panel of 10 anti-PSA monoclonal antibodies (mAbs). Methods. Enzyme-linked immunosorbent assay (ELISA), sandwich assays, and wester n transfer techniques were used to assess the PSA/hK2 cross-reactivity of the anti-PSA mAbs. Results. We did not detect the hK2 protein with any of the 10 anti-PSA mAbs under western transfer conditions. In ELI SA experiments, 8 of 10 mAbs exhibited hK2 cross-reactivity under cert ain conditions. However, no combination of mAbs tested in sandwich ass ays exhibited a signal in hK2 cross-reactivity experiments greater tha n 0.1% of the PSA signal. Conclusions. We have evaluated 10 anti-PSA m Abs and determined that despite the 80% homology between PSA and hK2 p roteins, cross-reactivity with hK2 by these antibodies would not signi ficantly affect the determination of PSA levels by means of sandwich a ssays. (C) 1997, Elsevier Science Inc. All rights reserved.