Studies of monoclonal and polyclonal anti-digoxin antibodies for serum digoxin radioimmunoassay.

We compared the advantages of monoclonal antibodies (produced by plasma cell-myeloma cell hybrid lines) and those of conventional antibodies in the radioimmunoassay of digoxin. It was found that antibodies produced by some hybrid cell lines (hybridomas) were highly specific for the digoxin structure; this way the cross-reactions to related structures (e.g. spironolactone) could be avoided. When the hybridoma lines were grown in ascites, the resulting fluid could have as high or higher titre than the serum of a hyperimmunized rabbit. The high titre, the specificity and the permanent growth of the hybridoma lines make them an optimal source of the specific antibody in clinical radioimmunoassays for the measurement of drug or hormone levels.