Effects of parenteral lipid emulsions with different fatty acid composition on immune cell functions in vitro

Background: Numerous studies suggest that immune function may be compromise d by lipid emulsions rich in polyunsaturated fatty acids (PUFAs). In our st udy, we compared the effect of a new olive oil-based lipid Emulsion (ClinOl eic) containing a moderate level of PUFAs, with emulsions based on soybean oil (Intralipid or Ivelip), on immune functions of human cell in vitro. Met hods: peripheral white blood cells were collected from healthy volunteers. Lymphocyte proliferation was evaluated by [H-3]-thymidine incorporation aft er stimulation with either phytohemagglutinin (PHA) or antibodies against T -cell specific antigens. Lymphocytes subsets and T-cell activation markers (CD25 and HLA-DR) were measured by flow cytometry. The release of cytokines (interleukin [IL]-2, IL-1 beta, and tumor necrosis factor-alpha [TNF-cl]) was measured by enzyme-linked immunosorbent. assay (ELISA), after lymphocyt es or monocytes/macrophages stimulation with PHA or lipopolysaccharide (LPS ). Results: A significant dose-dependent inhibition of thymidine incorporat ion was observed with Intralipid and Ivelip (incorporation down to 39.9% of control, p <.001) whereas ClinOleic showed no inhibitory effect. Activatio n antigen expression on both CD4(+) and CD8(+) T-cells tended to decrease w ith Intralipid (CD25: -53.4% on CD4(+) and -57.4% on CD8(+); HLA-DR: -61.5% on CD4(+) and -58.5% on CD8(+)) but not with ClinOleic (from -2.9% for CD2 5 on CD4(+) to 16.7% for HLA-DR on CD4(+)). Intralipid decreased significan tly IL-2 production (-39.0%, p <.05) whereas ClinOleic had little effect (- 13.0%, NS). Intralipid and ClinOleic tended to inhibit to a similar extent the release of pro-inflammatory cytokines (TNF-alpha: -21.5% and -34.8%, IL -1 beta: -45.1% and -40.3%; respectively). Conclusions: Our results suggest that an olive oil-based lipid emulsion could modulate immune response sele ctively, maintaining protective immunity and reducing inflammatory response . Olive oil may offer an immunologically neutral alternative to soybean oil for use in parenteral lipid emulsions.