Summary report of the TD-3 workshop: Characterization of 83 antibodies against prostate-specific antigen

Twelve research groups participated in the ISOBM TD-3 Workshop in which the reactivity and specificity of 83 antibodies against prostate-specific anti gen (PSA) were investigated. Using a variety of techniques including cross- inhibition assays, Western blotting, BIAcore, immunoradiometric assays and immunohistochemistry, the antibodies were categorized into six major groups which formed the basis for mapping onto two- and three-dimensional (2-D an d 3-D) models of PSA. The overall findings of the TD-3 Workshop are summari zed in this report. In agreement with all participating groups, three main antigenic domains were identified: free PSA-specific epitopes located in or close to amino acids 86-91; discontinuous epitopes specific for PSA withou t human kallikrein (hK2) cross-reactivity located at or close to amino acid s 158-163; and continuous or linear epitopes shared between PSA and hK2 loc ated close to amino acids 3-11. In addition, several minor and partly overl apping domains were also identified. Clearly, the characterization of antib odies from this workshop and the location of their epitopes on the 3-D mode l of PSA illustrate the importance of selecting appropriate antibody pairs for use in immunoassays. It is hoped that these findings and the epitope no menclature described in this TD-3 Workshop are used as a standard for futur e evaluation of anti-PSA antibodies.