Patent ID: 6107049
Filing Date: 2000-08-22
Classification: G01N,Y10S

Abstract:
A method for determining complexed prostate specific antigen (cPSA) in a blood sample, comprising the steps of:(a) contacting said blood sample with three anti-PSA antibodies to form a liquid test mixture:(i) a first anti-PSA antibody which binds to total PSA (tPSA),(ii) a second anti-PSA antibody which binds to tPSA, but which is substantially incapable of binding to PSA when PSA is bound by an antibody that binds to free PSA (fPSA) but not to cPSA, wherein one of said first and second antibodies is labeled (""labeled antibody"") and the other is immobilized or capable of being immobilized for purposes of separation from the liquid test mixture (""capture antibody""), and(iii) a third anti-PSA antibody, which third antibody binds to fPSA but not to cPSA, whereby binding of said third antibody to fPSA renders fPSA substantially incapable of being detected in the method,(b) separating said capture antibody from the liquid test mixture, and(c) measuring the label in the separated capture antibody phase or the remainder of the liquid test mixture.