Effect of medium- and long-chain triglycerides on human neutrophil migration

There is some controversy concerning the effect of intravenous long-chain triglyceride (LCT) emulsions on the phagocytic system and little is known about the effect of medium-chain triglyceride (MCT)-containing emulsions. We evaluated the chemotaxis and random migration of human neutrophils from 18 healthy adults after preincubation with the following fat emulsions: LCT, MCT and a mixture of 50% MCT and 50% LCT (MCT/LCT). Leukocyte-rich plasma (4 x 10(6) cells/ml) was diluted 4:1 (v/v) with commercial fat emulsions (LCT, MCT, or MCT/LCT, 1:1) or saline and tumbled at 20 cycles/min for 30 min at 37 degrees C. The final composition of the emulsion was 20 mg/ml fat, 0.24% egg yolk lecithin, and 0.5% glycerol and the dispersion was made isotonic by adding NaCl. In a second set of experiments, the LCT and MCT concentrations were adjusted to be equimolar. Leukocyte viability was > or = 95% after exposure to the treatment with fat emulsions. For emulsions with the same weight of each fat, random migration and chemotaxis of neutrophils were unaffected by the LCT emulsion but there was a significant decrease in both chemotaxis and random migration in MCT-(79 and 74%) or MCT/LCT-treated (60 and 56%) neutrophils. Similar results were obtained when LCT and MCT were equimolar. These results demonstrate an inhibitory effect of MCT on two human neutrophil functions which may be dose dependent.