Characterization of epitope structure for 53 monoclonal antibodies against prostate-specific antigen

Prostate-specific antigen (PSA) is the most widely used marker of prostate cancer. Assays for PSA are based on anti-PSA antibodies, and the characterization and selection of these antibodies is important for determining their optimum performance. In our study, we characterized the reactivity of 53 antibodies, submitted to the ISOBM TD-3 PSA Workshop, using free PSA, PSA complexed to alpha1-antichymotrypsin (ACT) and purified ACT. Immunoblotting was performed after native agarose gel or reducing sodium dodecyl polyacrylamide gel electrophoresis. Immunoblotting after agarose gel electrophoresis revealed 10 antibodies that recognized only the free form of PSA, and 43 antibodies that detected both free PSA and PSA-ACT. Immunoblotting of reducing sodium dodecyl-polyacrylamide gels showed the linear or conformation-dependent nature of the epitopes. Two antibodies specific for free PSA and 18 antibodies that recognized both free PSA and PSA-ACT complex recognized linear epitopes. Moreover, 7 antibodies also detected fragmented forms of PSA

The Environmental Determinants of Diabetes in the Young (TEDDY) Study

The etiology of type 1 diabetes (T1D) remains unknown, but a growing body of evidence points to infectious agents and/or components of early childhood diet. The National Institutes of Health has established the TEDDY Study consortium of six clinical centers in the United States and Europe and a data coordinating center to identify environmental factors predisposing to, or protective against, islet autoimmunity and T1D. From 2004-2009, TEDDY will screen more than 360,000 newborns from both the general population and families already affected by T1D to identify an estimated 17,804 children with high-risk HLA-DR,DQ genotypes. Of those, 7,801 (788 first-degree relatives and 7,013 newborns with no family history of T1D) will be enrolled in prospective follow-up beginning before the age of 4.5 months. As of May 2008, TEDDY has screened more than 250,000 newborns and enrolled nearly 5,000 infants--approximately 70% of the final cohort. Participants are seen every 3 months up to 4 years of age, with subsequent visits every 6 months until the subject is 15 years of age. Blood samples are collected at each visit for detection of candidate infectious agents and nutritional biomarkers; monthly stool samples are collected for infectious agents. These samples are saved in a central repository. Primary endpoints include (1) appearance of one or more islet autoantibodies (to insulin, GAD65 or IA-2) confirmed at two consecutive visits; (2) development of T1D. By age 15, an estimated 800 children will develop islet autoimmunity and 400 will progress to T1D; 67 and 27 children have already reached these endpoints

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 antigen (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 and 3-D) models of PSA. The overall findings of the TD-3 Workshop are summarized 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 without human kallikrein (hK2) cross-reactivity located at or close to amino acids 158-163; and continuous or linear epitopes shared between PSA and hK2 located close to amino acids 3-11. In addition, several minor and partly overlapping domains were also identified. Clearly, the characterization of antibodies from this workshop and the location of their epitopes on the 3-D model of PSA illustrate the importance of selecting appropriate antibody pairs for use in immunoassays. It is hoped that these findings and the epitope nomenclature described in this TD-3 Workshop are used as a standard for future evaluation of anti-PSA antibodies