Determination of cytotoxicity in vivo using 111indium-labeled human tumor cells

Abstract Loss of radioactivity from nude mice was determined after inoculation of human tumor cells prelabeled with [ 111 In]indium oxine ( 111 InOx). Elimination of 111 In was increased somewhat by treating the mice with diphtheria toxin (DT), which is toxic selectively for human cells compared to mice. Calcium disodium edetate (CaNa 2 EDTA), a metal chelating agent, facilitated elimination of 111 In and increased the difference in the rates of loss of radioactivity from mice bearing viable compared to DT-killed cells.