A simplified isotope release assay for cell-mediated cytotoxicity against anchorage dependent target cells

An assay for cell-mediated cytotoxicity has been developed in which anchorage-dependent target cells are cultured on small plastic beads in suspension. Confluent target cells on the beads are handled by methods appropriate to suspension-grown cells and labelled with chromium-51, iodine-125 and [3H]proline. Fetal human lung fibroblasts and HeLa cells were used as targets in model experiments measuring human natural killer cell activity. In 20 h experiments, chromium-51 was the most suitable isotope. In 40 h experiments, [3H]proline release assay was superior to chromium-51 and iodine-125 assays. The bead cytotoxicity assay offers a rapid and simple isotope release technique for anchorage dependent cells because no trypsinization and re-seeding of target cells is needed.