High-affinity monoclonal antibodies specific for human prostatic acid phosphatase.

We produced two monoclonal hybridoma cell lines that secrete IgG immunoglobulins with high affinities (Kd = 7.3 to 8.0 X 10(-11) mol/L, Ka = 1.25 to 1.37 X 10(10) L/mol) for 125I-labeled human prostatic acid phosphatase (PAP), and that specifically bind this enzyme from human serum. The antibodies were produced in high titers in murine ascitic fluid (700 mg/L) and in cell-culture media (30 mg/L) and were further purified to homogeneity by affinity chromatography on PAP- and Protein A-Sepharose CL-4B. After purification they were shown to be homogeneous by liquid chromatography. Both of these monoclonal antibodies exhibit strict specificity for PAP as determined by radioimmunoassay and by immunofluorescence studies of human pancreas, kidney, prostate, and leukocytes. The antibodies react only with the native form of the enzyme, as shown by the slot-immunoblotting method.