*2.5. FabF8:Stx2 Antibodies Avoid Apoptosis Induced by Stx2 in HGEC*

Apoptosis is the principal cell death mechanism triggered by Stx2. We previously showed that this toxin-induced necrosis and apoptosis in HGEC [28]. Following, we evaluated the ability of FabF8:Stx2 antibodies to avoid necrosis and apoptosis by analyzing HGEC stained with acridine orange/ethidium bromide by fluorescence microscopy (Figure 5A). The FabF8:Stx2 (1 μg/mL), significantly decreased the apoptosis caused by 0.5 ng/mL Stx2 in both experimental conditions (pre-incubation: 3.3 ± 0.9% and coincubation: 11.6 ± 1.4 vs. Stx2: 45.0 ± 2.0%, *p* < 0.05, *n* = 3). Furthermore, FabF8:Stx2 at pre-incubation conditions was more effective than co-incubation to prevent apoptosis (93.0 ± 0.90 % vs. 75.0 ± 1.4%, respectively, *p* < 0.05, *n* = 3) (Figure 5B). No significant differences were found for necrosis (Figure 5C).

**Figure 5.** FabF8:Stx2 prevents apoptosis induced by Stx2 in human glomerular endothelial cells (HGEC). The percentage of necrotic and apoptotic cells after 72 h of treatments was established morphologically by fluorescence microscopy after staining with acridine orange/ethidium (×200 and ×400). A representative experiment is shown in panel (**A**). Results are expressed as means ± SD of three experiments. Apoptosis (**B**), \* *p* < 0.05 for pre/co-incubation vs. Stx2. # *p* < 0.05 for pre-incubation vs. co-incubation. Necrosis (**C**), ns.
