Cytotoxicity of RFB4(dsFv)PE38 for various cell lines after a 24-hour incubation. [³H]leucine incorporation is expressed as a percentage of cpm incorporated by control cells incubated without immunotoxin. (○), CA46; (▵), JD-38; (+), Raji; (▪), Namalwa; (•), Daudi; (▴), HUT102. Data are representative of at least three trials for each cell line.