Influence of structurally different lipid emulsions on human neutrophil oxygen radical production

Background The aim of this study was to evaluate immunomodulatory propertie s of lipid emulsions applied in parenteral nutrition by measuring neutrophi l oxygen radical production (the 'respiratory burst') after lipid incubatio n. Materials and methods Neutrophils, isolated from the blood of 10 healthy in dividuals, were incubated in medium or in lipid emulsions in a physiologica l concentration (2.5 mmol L-1) containing long-chain [Intralipid (LCT)], mi xed medium and long-chain [Lipofundin (LCT/MCT)] or structured triglyceride s (SL). After washing and stimulation with phorbol 12-myristate 13-acetate (PMA) or serum-treated zymosan (STZ) particles, the respiratory burst was e valuated by measuring maximum oxygen uptake, superoxide and hydrogen peroxi de production rates and chemiluminescence. Results Unlike LCT and SL, LCT/MCT increased PMA- and STZ-induced oxygen up take rate by 45% and 31% respectively (both P=0.006 compared with medium) a s well as superoxide (+56%, P=0.006) and hydrogen peroxide (+14%, P=0.04) p roduction, within 5 min after stimulation. Increased LCT/MCT-mediated early respiratory burst was confirmed by decreased PMA- (-65%) and STZ-stimulate d (-54%) chemiluminescence peak time (time after stimulation to peak) in co mbination with unchanged peak height (maximum rate of radical production). Late respiratory burst (within 2 h) of LCT/MCT, indicated by overall lumine scence (overall radical production), remained unchanged (PMA) or decreased (STZ, P=0.02). The addition of 25 mmol L-1 LCT/MCT or MCT emulsion to unsti mulated neutrophils, in contrast to LCT and SL, resulted in significant lum inescence. Conclusions Early neutrophil respiratory burst is accelerated by the LCT/MC T emulsion Lipofundin, whereas LCT (Intralipid) and structured lipid emulsi ons exert no effect. MCT-containing emulsions, contrary to LCT and structur ed lipid emulsions, can induce oxygen radical production in unstimulated ne utrophils.