The preparation, characterization and application of monoclonal antibodies to human prostatic acid phosphatase (PAP).

Hybridoma cells secreting anti-PAP were produced by fusion of NS-1 myeloma cells with spleen cells from immunized Balb/c mice. Three of 32 hybrids secreted antibodies. Dilution cloning of the two hybrids producing the highest antibody titres showed that each antibody was monoclonal. One clone from each hybrid (clones ES2 and ES8) was selected for further study. The specificity of the antibodies appeared satisfactory, no inhibition of 125I-PAP binding to antibody being seen with extracts of bone, intestine, kidney, leucocytes, liver or lung. The association constants of the antibodies from ES2 and ES8 were 1.7 X 10(8) and 1.7 X 10(9) l/mol respectively, both were of the IgG1 class. For the immunoradiometric (IRMA) assay of serum PAP 125I-labelled monoclonal antibody was incubated with serum and the PAP-labelled antibody complex was separated by addition of solid-coupled polyclonal anti-PAP. The wide working range of the response curve (0.3-400 micrograms/l) and the rapid analysis time (4 h) offer practical advantages over RIA procedures. Clinical evaluation of the assay is in progress. ES8 antibody also appears to have good specificity for immunocytochemical applications. Localisation of micrometastases in bone in prostatic carcinoma was readily achieved.