特異性:8A4 reacts with free A-subunits of Diphtheria toxin. It does not react with the whole Diphtheria toxin and free B-subunit of Diphtheria toxin. 7F2 reacts with the epitope exposed on free A-subunit and on whole Diphtheria toxin molecule. It does not react with free B-subunit of Diphtheria toxin.