Phagocytosis and Killing of Candida albicans by Human Neutrophils After Exposure to Structurally Different Lipid Emulsions

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Abstract
Background: To test the hypothesis that structurally different lipid emulsions have distinct immune‐modulating properties, we analyzed the elimination of Candida albicans by neutrophils after exposure to various emulsions. Methods: Neutrophils from 8 volunteers were incubated in physiologic 5 mmol/L emulsions containing long‐chain‐(LCT), medium‐chain‐ (MCT), mixed LCT/MCT‐, α‐tocopherol‐enriched LCT/MCT (LCT/MCT‐E), or structured lipids (SL). After washing, the neutrophils were incubated with C. albicans. Phagocytosis was measured as the number of yeast‐associated neutrophils relative to the total neutrophil count. Killing was expressed as the percentage of Candida survival relative to the initial yeast cell count. Results: No significant differences in yeast‐neutrophil association could be demonstrated after neutrophil incubation in various lipid emulsions or medium, after correction for non‐specific adhesion. However, although Candida survival after 1 hour incubation with non‐lipid‐exposed neutrophils amounted to 53% ± 11% and was not influenced by LCT (60% ± 11%), LCT/MCT (78% ± 7%), LCT/MCT‐E (72% ± 12%), and SL (67% ± 6%), pure MCT (70% ± 13%) significantly impaired the killing capacity of neutrophils. Conclusions: The decreased killing capacity of neutrophils after exposure to medium‐chain fatty acid‐containing emulsions and the absence of this effect with LCT suggest that lipid emulsions influence the elimination of C. albicans depending on the triglyceride chain length. (Journal of Parenteral and Enteral Nutrition 25: 9–13, 2001)