Unsaturated long-chain fatty acids induce the respiratory burst of human neutrophils and monocytes in whole blood

BACKGROUND: It is increasingly recognized that infectious complications in patients treated with total parenteral nutrition (TPN) may be caused by altered immune responses. Neutrophils and monocytes are the first line of defence against bacterial and fungal infection through superoxide anion production during the respiratory burst. To characterize the impact of three different types of lipid solutions that are applied as part of TPN formulations, we investigated the unstimulated respiratory burst activation of neutrophils and monocytes in whole blood. METHODS: Whole blood samples were incubated with LCT (Intralipid(®)), LCT/MCT (Lipofundin(®)) and LCT-MUFA (ClinOleic(®)) in three concentrations (0.06, 0.3 and 0.6 mg ml(-1)) for time periods up to one hour. Hydrogen peroxide production during the respiratory burst of neutrophils and monocytes was measured by flow cytometry. RESULTS: LCT and LCT-MUFA induced a hydrogen peroxide production in neutrophils and monocytes without presence of a physiological stimulus in contrast to LCT/MCT. CONCLUSION: We concluded that parenteral nutrition containing unsaturated oleic (C18:1) and linoleic (C18:2) acid can induce respiratory burst of neutrophils and monocytes, resulting in an elevated risk of tissue damage by the uncontrolled production of reactive oxygen species. Contradictory observations reported in previous studies may in part be the result of different methods used to determine hydrogen peroxide production.