Figure 4

Cytotoxicity of IL2 pre-activated human T cells to KG1a cells in different effector to target (E/T) ratios mediated by different concentrations of fusion proteins in a non-radioactive cytotoxicity assay. (A) Cytotoxicity of T cells in the presence of antiCD3Fv-⊿IL3. (B) Cytotoxicity of T cells in the presence of ds-antiCD3Fv-⊿IL3. Concentrations of fusion proteins were different (500, 50, 5 ng/mL). E/T cell ratios ranged from 25:1 to 3:1. (C) Lysis of target cells by T cells mediated by PBS, ds-antiCD3Fv-⊿IL3, antiCD3Fv-⊿IL3, and the control diabody antiCD19 × antiCD3. The concentration of all fusion proteins was 500 ng/mL. CD123-negative cell line (D) THP1 and (E) NB4 were included as a control. (F, G) Ratios of apoptotic cells mediated by fusion proteins (500 ng/mL) combined with pre-activated T cells at E/T ratio of 25:1. PBS and antiCD19 × antiCD3 are used as a control. **P < 0.01 vs PBS. Data shown are the mean ± SD of three repeated experiments.