Cytokines induce a slight upregulation of P2X7 receptor. (A) CHME-5 cells were treated for 3, 6, 15, and 24 h with interferon (IFN)-γ or interleukin-4 (IL-4) (20 ng ml−1) and stained for P2X7; the normalized expression levels, calculated from four independent experiments (mean ± SEM), are reported on the graphs at the right side of the figure. One-way Anova plus Dunnett’s post hoc test were used for statistical analysis (*p: 0.0361). A significant increase of the P2X7 levels was measured only after 6 h of IFN-γ treatments. The scale bar in the upper right side of the image corresponds to 10 µm. (B) ATP-containing granules labeled by quinacrine staining of live CHME-5 cells were imaged by widefield microscopy followed by image deconvolution. Scale bars: 10 µm. (C) Extracellular ATP (exATP) quantified by a luminescence assay; to reduce exATP degradation the ecto-ATPase inhibitor ARL67156 was maintained in the culture medium throughout the treatments. Data represent the mean ± SEM of three independent experiments. Student’s t-test was used for statistical analysis. No significant differences were found between controls and stimulated cells.