A highly sensitive enzyme-linked immunoassay for serum free prostate specific antigen (f-PSA)

Monoclonal antibodies (MAbs) were generated against human prostate specific antigen (PSA) to allow development of a sensitive free-PSA (f-PSA) assay. Of a total of 211, 12 could detect only f-PSA, the other 199 MAbs binding t o both f-PSA and complex-PSA. In the present study, one MAb (no. 5C6) speci fic for f-PSA and another (no. 79) reacting with both forms were used to de velop an enzyme-linked immunoassay (ELISA) for serum f-PSA. The detection l imit was established as 0.008 mu g/l (n = 20, mean of zero standard + 3 S.D .) and the average recovery of f-PSA was 93-102%. The within-run and betwee n-day coefficient of variation (CV) varied from 5.4-7.4% and 4.8-6.5%, resp ectively. The cross-reactivity of the assay to PSA-alpha(1)-antichymotrypsi n complex was determined to be <0.4%. (C) 1999 Elsevier Science B.V. All ri ghts reserved.