Cross-reactivity of ten anti-prostate-specific antigen monoclonal antibodies with human glandular kallikrein.
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.
Corey
E
E
Tumor Immunology Laboratory of the Urology Department, Medical School, University of Washington, Seattle 98195, USA.
Buhler
K R
KR
Vessella
R L
RL
D000911:Antibodies, Monoclonal / Q000276:immunology*; D003429:Cross Reactions; D006801:Humans; D007610:Kallikreins / Q000276:immunology*; D017430:Prostate-Specific Antigen / Q000276:immunology*
D000911:Antibodies, Monoclonal; D007610:Kallikreins; D017430:Prostate-Specific Antigen