Selective in vitro toxicity of purothionin conjugated to the monoclonal antibody 225.28S to a human high-molecular-weight melanoma-associated antigen.

The toxic agent purothionin was conjugated to the monoclonal antibody 225.28S to a human high-molecular-weight melanoma-accociated antigen. The toxic conjugate displayed in vitro toxicity to cultured human Colo 38 melanoma cells as indicated by reduced uptake of 3H-thymidine following a 24-h incubation and loss of cell viability following a 7-day incubation. The effect is dose-dependent and is specific since addition of the toxic conjugate to a cultured Raji B lymphoid cells did not affect their 3H-thymidine uptake or their viability.