Effect of DT on the respiratory burst of PMN maintained in culture with GM-CSF. DT specifically suppressed the priming effect of GM-CSF, but was largely ineffective toward LPS (P < .05). PMN (3 × 10⁵/well) were cultured for 21 hours in the presence or absence of 0.5 ng/mL GM-CSF with or without 10⁻⁸ mol/L DT before stimulation with 100 nmol/L fMLP. Data represent the mean values (±SD) of SOD-inhibitable O₂⁻ release from triplicate assays for each condition. Similar results were obtained in 3 separate experiments.