Alteration of the structure and function of guinea pig peritoneal macrophages by a soybean oil emulsion

Studies in humans who have received Intralipid (IL) have demonstrated the presence of a fat pigment and fat droplets in reticuloendothelial phagocytic cells. Clinical data and in vitro studies suggest that these cells do not function normally. We have studied the effect of IL on the morphology and function of guinea pig peritoneal macrophages in vitro. Starch-induced macrophages were exposed to IL for up to 48 hours. Ingestion of increasing amounts of IL over the 48-hour period was confirmed by transmission electron microscopy and by oil red O stain. The uptake of the IL was associated with marked morphologic changes characterized by a decreased ability of the cells to spread and by a decrease in the number and degree of complexity of the membrane ruffles. The ingestion of IL also resulted in decreased capacity of the cells to associate with latex beads (5.7 mu in diameter) or Candida albicans and decreased capacity to adhere to and ingest sheep erythrocytes coated with IgG. After ingestion of latex beads 0.46 mu in diameter, which are similar in size to IL particles, macrophages had normal morphology and function, indicating that neither the morphologic nor functional abnormalities were due to a nonspecific effect of ingestion of small particles. Alterations of human reticuloendothelial macrophage function similar to the effects observed here could compromise host defense against infection.