title: Cross-reactivity of ten anti-prostate-specific antigen monoclonal antibodies with human glandular kallikrein.
abstract: OBJECTIVE
  Prostate-specific antigen (PSA) is commonly used as a marker for prostate disease. Prostate epithelium expresses both PSA and human glandular kallikrein (hK2) proteins, which share 80% sequence homology. The immunologic cross-reactivity of these two proteins could potentially interfere with determination of PSA levels in diagnoses of prostate cancer. We set out to determine the extent of this cross-reactivity for a panel of 10 anti-PSA monoclonal antibodies (mAbs).
  
  
  METHODS
  Enzyme-linked immunosorbent assay (ELISA), sandwich assays, and western 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 ELISA experiments, 8 of 10 mAbs exhibited hK2 cross-reactivity under certain conditions. However, no combination of mAbs tested in sandwich assays exhibited a signal in hK2 cross-reactivity experiments greater than 0.1% of the PSA signal.
  
  
  CONCLUSIONS
  We have evaluated 10 anti-PSA mAbs and determined that despite the 80% homology between PSA and hK2 proteins, cross-reactivity with hK2 by these antibodies would not significantly affect the determination of PSA levels by means of sandwich assays.
authors.affiliation: Tumor Immunology Laboratory of the Urology Department, Medical School, University of Washington, Seattle 98195, USA.
authors.forename: E
authors.initials: E
authors.lastname: Corey
authors.forename: K R
authors.initials: KR
authors.lastname: Buhler
authors.forename: R L
authors.initials: RL
authors.lastname: Vessella
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D003429:Cross Reactions; D006801:Humans; D007610:Kallikreins / Q000276:immunology*; D017430:Prostate-Specific Antigen / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007610:Kallikreins; D017430:Prostate-Specific Antigen