Figure 6. Antibody-dependent enhancement of λ-phage mediated gene expression in FcγRI-positive cells is prevented by inhibitors of endosomal acidification.

Luciferase encoding λ phage particles were preincubated with a gpD-specific rabbit antiserum (λ luc + gpD) prior to addition to target cells at a MOI of 10⁶. Phage were then added to parental CV1 cells (open bars) or to CV1 cells stably expressing FcγRI together with the accessory γ-chain subunit (black bars; FcγR1 γ+). Cells were pretreated with medium alone (no drug), bafilomycin A1 (20 nM and 100 nM) or monensin (20 µM), for 30 minutes at 37°C before the addition of bacteriophage. Forty-eight hours after the addition of phage, cells were harvested, and luciferase activity was measured in cell lysates. The data represent mean values calculated from triplicate samples; error bars represent the standard deviation. The asterisks (***) denote a statistically significant difference from control cells (no drug) (p value < 0.001, one-way ANOVA).