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 compromised by lipid emulsions rich in polyunsaturated fatty acids (PUFAs). In our study, we compared the effect of a new olive oil-based lipid Emulsion (ClinOleic) containing a moderate level of PUFAs, with emulsions based on soybean oil (Intralipid or Ivelip), on immune functions of human cell in vitro. Methods: peripheral white blood cells were collected from healthy volunteers. Lymphocyte proliferation was evaluated by [H-3]-thymidine incorporation after 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 lymphocytes or monocytes/macrophages stimulation with PHA or lipopolysaccharide (LPS). Results: A significant dose-dependent inhibition of thymidine incorporation was observed with Intralipid and Ivelip (incorporation down to 39.9% of control, p <.001) whereas ClinOleic showed no inhibitory effect. Activation antigen expression on both CD4(+) and CD8(+) T-cells tended to decrease with 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 CD25 on CD4(+) to 16.7% for HLA-DR on CD4(+)). Intralipid decreased significantly 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 selectively, maintaining protective immunity and reducing inflammatory response. Olive oil may offer an immunologically neutral alternative to soybean oil for use in parenteral lipid emulsions.