The effects of intralipid and heparin on human monocyte and lymphocyte function

A group of patients were studied during the infusion of Intralipid as part of a parenteral nutrition regimen. Peripheral blood lymphocyte function was unaffected, but monocyte function (chemotaxis) was significantly depressed. A group of healthy volunteers received an intravenous bolus of 20% Intralipid. Blood was taken before and 15 min afterward for immunological studies, and the same changes were seen following Intralipid. Prior subcutaneous injection of 5000 U of heparin did not affect either immunological parameter, but completely prevented the changes in monocyte function caused by Intralipid. Electronmicrographs of monocytes from volunteers after injection of Intralipid, and autoradiographs of cells incubated with 14C-Intralipid in vitro, showed phagocytosis of fat particles by monocytes. These data suggest that Intralipid can have potentially serious side effects on the immune system, and that they may be alleviated by the use of subcutaneous heparin.