Fig. 4.

Comparison of the impact of standard and metronomic TMZ regimens on Treg function. Four groups of three rats were either inoculated with RG2 cells on day-12 or left tumor-free (Naive). Treatment, which consisted of vehicle alone (Untreated), TMZ 30 mg/kg per day for 5 days (Std TMZ) or TMZ 0.5 mg/kg per day for 3 weeks (Metronomic TMZ) was administered to tumor-bearing rats. Animals were sacrificed on day 21 and T cells were isolated from the collected spleens. 2 x 10⁶ splenic T cells depleted (open bars) or not (filled bars) of Treg were incubated for 3 days with antiCD3 mAb. Supernatants of these cultures were harvested and IFN-γ concentrations were determined by an ELISA test. Results are expressed as mean ± SD of IFN-γ levels measured in three splenic T cell cultures obtained from three different rats. IFN-γ levels observed in cultures depleted or not of Treg were compared within each group. NS not significant; * p < 0.05; paired Student’s t test