Fig. 5

Cytotoxic activity of recombinant TTC-ETA’ on hybridoma cells. The hybridoma cell lines 5E4 (▼; n = 4) and 8.18-C5 (■; n = 3) were incubated with serial dilutions of TTC-ETA’ (a) and TTC (b) in complete RPMI 1640 cell culture medium. After incubation at 37 °C and 5 % CO₂ for 72 h, the cells were refreshed with 50 μl RPMI 1640 medium containing XTT/phenazine methosulfate and incubated for another 4 h. Absorbance was measured at 450 nm and 630 nm on an ELISA reader. The half maximal inhibitory protein concentration (EC₅₀) relative to untreated control cells was calculated using GraphPad Prism software. The recombinant TTC-ETA’ exhibits a dose-dependent cytotoxicity on the target hybridoma cell line 5E4 with an EC₅₀of 1.3 nM ± 0.4 nM but has no effect on the control cell line 8.18-C5. These data represent the mean ± SD of three independent experiments performed in triplicates. *, P < 0.05; ** , P < 0.01; P < 0.001 versus control cells