Ricin B chain converts a non‐cytotoxic antibody‐ricin A chain conjugate into a potent and specific cytotoxic agent

Abstract
We report the conversion of a non‐cytotoxic antibody‐ricin A chain conjugate to one displaying specific cytotoxic effects comparable with that of native ricin, by the addition of ricin B chain as a second stage reagent. The results suggest that this conversion is achieved by the association of the added B chain with the A chain of the conjugate, and not through a primary binding of B chain at the cell surface.