The invention features radiolabeled immunotoxins, and radiolabeled multimeric (e.g., dimeric) immunotoxins. Also encompassed by the invention are methods of killing pathogenic cells, imaging, and making radiolabeled immunotoxins and radiolabeled multimeric immunotoxins.
 This application claims priority of U.S. provisional application Ser. No. 60/219,759, filed Jul. 20, 2000.
 Some of the research described in this application was supported by a grant (no. DE-FG02-96ER62181) from the U.S. Department of Energy. The U.S. government may have certain rights in the invention.