Immunotoxins Containing Ricin A Or B Chains with Modified Carbohydrate Residues Act Synergistically in Killing Neoplastic B Cells In Vitro*

Partially deglycosylated (dg) ricin A and B chains were coupled to rabbit anti-human Ig (IT-dg-A) and goat anti-rabbit Ig (IT-dg-B), respectively. The deglycosylation was accomplished by treating intact ricin (before separation into its constituent chains) with a mixture of sodium metaperiodate and sodium cyanobrohydride. The two immunotoxins (ITs) acted synergistically in vitro to kill Daudi cells, albeit to a four-to-eight-fold lesser degree than ITs prepared with native A and B chains.