Granulocyte oxidative activity after thermal injury.

BACKGROUND. Alterations in granulocyte function after thermal injury have been described. We have serially studied the level of granulocyte cytosolic peroxidase activity in 23 thermally injured patients during the first 6 weeks after injury. The patients' mean age and burn size were 35.1 +/- 15.7 years and 41.6% +/- 16.8% (range, 18% to 88%), respectively. Fourteen patients had concomitant inhalation injury, and the overall mortality rate was 4.3%. METHODS. Purified granulocytes were obtained from peripheral blood after red cell lysis and Ficoll-Hypaque (Pharmacia Inc., Piscataway, N.J.) gradient separation. Cells were loaded with dichlorofluorescin diacetate, and baseline fluorescence was measured by flow cytometry. After phorbol myristate acetate stimulation, fluorescence was measured again. Cells from unburned normal subjects were used as daily controls. RESULTS. The data are expressed as percent of stimulated control granulocyte fluorescence. Unstimulated patient granulocytes demonstrated a significantly higher baseline activity than did unstimulated controls (22.9% vs 15.4%; p < 0.05). Mean fluorescence from stimulated granulocytes was 114% of the control values (p < 0.05). CONCLUSIONS. Granulocytes from thermally injured patients exhibited a baseline increase in cytosolic oxidase activity, suggesting in vivo activation and a greater than normal oxidase activity after in vitro stimulation.