Production and characterization of monoclonal and polyclonal antibodies against digoxin

Three hybridoma cell lines (DIG 64. 2B. 5, DIG 104. H10.1 and DIG 222. 4D. 5) producing monoclonal antibodies against digoxin were established, and the properties of these monoclonal antibodies were characterized and compared with three polyclonal rabbit anti-digoxin antisera. Both polyclonal and monoclonal antibodies gave association constants ranging from 10(9) to 10(10) (M-1). The monoclonal antibodies were of the IgG1(kappa) or IgG2b(kappa) subclass. Cross-reactivities of these monoclonal antibodies and polyclonal antisera with various related cardenolides and their aglycones were determined by competitive radioimmunoassay. The monoclonal antibodies were specific for digoxigenin-containing glycosides such as lanatoside C and deslanoside, but not for digitoxigenin-containing glycosides. On the other hand, the specificities of the polyclonal antisera were less strict than the monoclonal antibodies and relatively cross-reactive with digitoxin. It was shown that the RIA for digoxin using DIG 64. 2B. 5 is sensitive enough to detect 0.2-0.3 nM (30-60 pg/tube) of digoxigenin-containing cardenolides.