Growth curves of genetically modified T cells. Patient PBMCs were transfected with the scFvFc:ζ plasmid by electroporation after stimulation with OKT3. For patients A, B, and D, populations of G418-resistant T cells were generated by limiting dilution, and T-cell cultures exhibiting the most favorable cytotoxicity and growth profiles were selected for expansion to therapeutic numbers. For patients F through I, G418-resistant cells were grown as bulk cultures.