Relative affinity and specificity of monoclonal antibodies against prostate-specific antigen

The relative affinities of a panel of antibodies submitted to the ISOBM TD-3 PSA Workshop were determined by direct-binding ELISA. The Workshop antibodies were also tested for reactivity with the prostate-specific antigen alpha1-antichymotrypsin complex (PSA-ACT) and cross-reactivity with porcine pancreatic kallikrein. There was a wide range of affinities observed for the panel of antibodies. Twelve antibodies failed to react with the PSA-ACT complex, and 1 antibody was found to recognize an epitope on ACT but not on PSA. Only 2 antibodies were found to react with porcine pancreatic kallikrein, a protein with 64% sequence homology with human glandular kallikrein-2 (hK2).