Intralipid effects on reticuloendothelial function.

Malnourished patients frequently received parenteral nutrition with Intralipid, a lipid emulsion that accumulates in the reticuloendothelial tissue in some patients. To examine the potential of this emulsion as a risk factor for infection, I evaluated its effect on peritoneal clearance processes and on macrophage function. Mice treated with Intralipid (0.5 ml intraperitoneally) twice daily for 4 days had delayed clearance of Staphylococcus aureus from the peritoneal cavity and had increased staphylococcal dissemination to renal tissue. However, this regimen did not alter the neutrophil influx into the peritoneum elicited by this bacterial challenge. Intralipid also delayed the clearance of inert carbon particles from the peritoneal cavity. Peritoneal macrophages incubated with Intralipid (40% vol/vol) in tissue culture media for 18 hr became rounded and more phase dense, and these cells had multiple homogeneous cytoplasmic deposits. This Intralipid exposure reduced phagocytic and pinocytic activities in these monolayers, and the phagocytic defect persisted for at least 24 hr after cells were removed from media supplemented with Intralipid. In summary, these results demonstrate that Intralipid inhibits peritoneal clearance processes and that this alteration probably reflects impaired macrophage (free cells) and reticuloendothelial function. In some patients this form of nutritional therapy may increase the risk of infection.