AN ANTIDIGOXIN MONOCLONAL-ANTIBODY SEEMS TO EXPRESS MORE THAN ONE FUNCTIONAL PARATOPE

An anti-digoxin monoclonal antibody (mAb 4G3) has been Produced and ch aracterized with respect to its fine specificity and affinity. In an i ndependent series of experiments anti-idiotypic monoclonal antibody (m Ab 7G9) was selected which reacted with the antigen-binding center of an anti-human chorionic gonadotropin monoclonal antibody (anti-hCG mAb 1B10). In detailed studies on its binding characteristics it has been shown that mAb 4G3 binds to an anti-idiotypic monoclonal antibody mAb 7G9 in solution. Western blotting experiments showed that mAb 4G3 rea cted against antiidiotypic antibody under non-reducing conditions, onl y. Moreover, mAb 4G3 has been shown to express self-binding properties . Absorption with saturating amounts of its specific hapten, i.e. digo xin, did not change the binding of mAb 4G3 to anti-idiotypic antibody and its self-binding ability. It is speculated on the basis of these d ata that mAb 4G3 possesses more than one functional paratope.