Fig. 7

Up-regulation of CD8⁺ T cells surface markers CD69 (early), CD71 (middle) and CD25 (late) by Stx1B-scFv OKT3 lectibody. Gb3⁺ Ramos or Gb3⁻ Namalwa cells were co-cultured with PBMCs in the effector-to-target (E:T) ratio of 5:1 and purified Stx1B-scFv OKT3 lectibody (35.6 nM). Mean Fluorescence Intensity (MFI) data from three different donors were analyzed in flow cytometry from live CD8⁺ gated PBMCs. Results are expressed as a mean ± SD (n = 3) from separate experiments. After 24 h, the surface expression of T cell activation surface markers a CD69 and b CD71 was determined. c CD71 and d CD25 surface expression was monitored at 48 h following co-incubation of target and effector cells in presence of lectibody. CD8⁺ T cells were significantly activated when co-incubated with Gb3-expressing tumor cells and Stx1B-scFv OKT3, while they remained in a resting state when treated with Gb3-negative cells and lectibody. Statistical differences were determined with a two-tailed, unpaired t-test between control and each treatment group. Tests with a p-value ≤ 0.05 are considered statistically significant and marked with an asterisk (*), and p-values ≤ 0.01 are shown as two asterisks (**)