Growth inhibition by huTR. A total of 10⁴ CD30⁺ Karpas 299 cells or CD30⁻ HD-MY-Z cells per well were incubated with increasing amounts of the huTR or scFv-Fc. The number of viable cells was counted after 72 hours. Each data point represents triplicate cell counting of samples; error bars indicate standard deviation. (A) Two different variants of huTRs using either scFv 2A1 (•) or scFv 4E3 (■) were used. Negative control: huTR with 2A1 on CD30⁻ cells (▴). (B) huTR with scFv 4E3 as targeting domain (■, ▴) or its scFv-Fc part without RNase moiety (•, ◆) were used on either CD30⁺ (■, •) or CD30⁻ lymphoma cells (▴, ◆).