Cholesterol flux in cholesterol ester-loaded macrophages in an in vitro perfusion system

Cholesterol ester-loaded J774 macrophages attached to microcarrier beads were perfused or incubated with lipoproteins in vitro. Cholesterol influx was reduced by decreasing LDL cholesterol, efflux was promoted by increasing HDL cholesterol or by adding apolipoprotein A-I/phosphatidylcholine complexes to the perfusate or incubation medium. Addition of sera obtained from patients after LDL apheresis or plasma exchange resulted in much smaller increments in cell cholesterol than pretreatment sera, due to decreased influx, but efflux was unchanged despite the reduction in HDL cholesterol by plasma exchange. These data suggest that extracorporeal cholesterol removal promotes mobilization of intracellular cholesterol ester mainly by reducing cholesterol influx.