Reactivity of 77 antibodies to prostate-specific antigen with isoenzymes and complexes of prostate-specific antigen

Seventy-seven antibodies submitted to the ISOBM TD-3 PSA Workshop (TD-3.1 a nd TD-3.2) were characterized by measuring their reactivity with isoenzymes of free prostate-specific antigen (PSA), PSA complexed to alpha(1)-antichy motrypsin (PSA-ACT) and al-proteinase inhibitor (PSA-API). Antibodies were classified into 15 distinct groups according to their reaction profiles wit h the various isoenzymes. Some antibodies recognizing both free and complex ed PSA were inaccurate in measuring total PSA. Eight of the 9 free PSA-spec ific antibodies cross-reacted more with PSA-API than with PSA-ACT, while 1 antibody reacted less with PSA-API than PSAACT. From the panel of antibodie s 39 reacted with both free and complexed PSA and were classified as total PSA antibodies.