Effects of structurally different lipid emulsions on human neutrophil migration

Aim: To test the hypothesis that structurally different lipid emulsions hav e distinct immunomodulatory properties, we analysed neutrophil migration in the presence of various lipid emulsions. Method: Neutrophils of 8 voluntee rs were pre-incubated in medium or physiological 2.5 mM emulsions containin g long-chain (LCT), medium-chain (MCT), mixed LCT/MCT alpha -tocopherol-enr iched LCT/MCT LCT/MCT-E) or structured triglycerides (SL). Thereafter, the cells were put on top of 3 mum-pore-sized cell culture filters and incubate d for one hour in the presence or absence of a chemo-attractant. Neutrophil migration was measured as the percentage of cells that had passed the filt er in the presence (chemotaxis) or absence (random migration) of a chemotac tic factor. Results: Compared to lipid-free incubation (19+/-1%) random neu trophil migration significantly decreased with LCT/MCT (11+/-2%), LCT/MCT-E (12+/-2) and MCT (5 +/- 2%), while LCT (18 +/- 3%) and SL (20 +/- 1%) had no effect. N-formyl-methionyl-leucyl-phenylalanine- (fMLP, 10(-8) M) or zym osan-activated-serum-induced (ZAS, 10%) filter passage under lipid-free con ditions amounted to 61 +/- 14% and 70 +/- 13%, respectively. These values d ecreased with LCT/MCT to 11 +/- 9% and 15 +/- 7%; with LCT/MCT-E to 18 +/- 10% and 28 +/- 12%; with SL to 39 +/- 18% and 57 +/- 14%, and with MCT to 5 +/- 2% and 10 +/- 6%, (all P < 0.01), while LCT had no effect. Compared to LCT/MCT, the a-tocopherol-enriched formulation significantly increased ZAS - and fMLP-induced chemotaxis. fMLP-induced chemotaxis decreased in direct proportion to LCT/MCT triglyceride concentration. Conclusions. Human neutro phil migration is distinctively inhibited by structurally different lipid e mulsions, depending on triglyceride chain-length and concentration as well as a-tocopherol content. (C) 2000 Harcourt Publishers Ltd.