Rat peritoneal PMNs were activated by PMA, TNF-α, or IFN-γ to release hydrogen peroxide. PMNs (5.0 × 106/ml) cultured with or without PMA (0.64 μM), TNF-α (2000 U/ml), or IFN-γ (2000 U/ml) stimulation released high levels of hydrogen peroxide. # = significantly different (P < 0.05) from PMN only. n = 6. Number of experiment replication = 3.