HUMAN PERITONEAL MONOCYTIC CELLS - LIPOPROTEIN UPTAKE AND FOAM CELL-FORMATION

Human peritoneal cells isolated from dialysis effluent have in vivo ma turated human macrophages that could serve as a model for studying lip oprotein metabolism and foam cell formation. We previously characteriz ed the low density lipoprotein (LDL) and acetylated LDL (acetyl-LDL) r eceptor activities of human total peritoneal cells. Now, we provide ev idence that both LDL and acetyl-LDL stimulate acylCoA cholesterol:acyl transferase (ACAT) activity of peritoneal cells. Prolonged incubation of cells with LDL results in suppression of ACAT activity, while incu bation with acetyl-LDL results in elevated and sustained enzyme activi ty. When human peritoneal cells were analyzed using flow cytometry, th e cell population showed reactivity for CD2, CD4, CD8, CD20, CD14 and HLA-DR antigens. Purified human peritoneal mononuclear cells degraded LDL. Human peritoneal macrophages formed foam cells when exposed to LD L or acetyl-LDL in culture, and lipid deposition increased with incuba tion time. Macrophages incubated in the presence of butylated hydroxy toluene and LDL did not form foam cells.