FIGURE 7.

Human eosinophils express the P2Y₂ receptor, and anti-P2Y₂ Ab blocks the eosinophils’ responses to exogenous ATP, UTP and MSU crystals. (A) Eosinophils were incubated with rabbit anti-human P2Y₂ Ab or control Ab. Cells were then incubated with FITC-conjugated goat anti-rabbit IgG, fixed with 1% paraformaldehyde, and analyzed by flow cytometry. Left panel shows a representative histogram. Right panel shows a summary with eosinophils from six different donors. Results show the mean±SEM of mean fluorescence intensity (MFI). *; significant differences compared with control Ab (p<0.05). (B) Eosinophils were preincubated with or without rabbit polyclonal anti-P2Y₂ Ab or control Ab (20 μg/ml) for 15 minutes and cultured with medium alone, 100 μM ATP or 100 μM UTP for 24 h at 37 °C. Concentrations of IL-6 and IL-8 in the supernatants were measured by ELISA. Results show the mean±SEM from five different eosinophil preparations. **; significant differences compared with control Ab (p<0.01). (C) Eosinophils were preincubated with or without anti-P2Y₂ Ab or control Ab (1-30 μg/ml) for 15 minutes and cultured with 0.1 mg/ml MSU crystal suspension for 24 h at 37 °C. Concentrations of IL-6 and IL-8 in the supernatants were measured by ELISA. Results show the mean±SEM from six different eosinophil preparations. **; significant differences compared with control Ab (p<0.01).