Atherosclerotic cardiovascular disease (ASCVD) contributes to morbidity and mortality in systemic lupus erythematosus (SLE). Immunologic derangements may disrupt cholesterol balance in vessel wall monocytes/macrophages and endothelium. We determined whether lupus plasma impacts expression of cholesterol 27-hydroxylase, an anti-atherogenic cholesterol-degrading enzyme that promotes cellular cholesterol efflux, in THP-1 human monocytes and primary human aortic endothelial cells (HAEC). THP-1 monocytes and HAEC were incubated in medium containing SLE patient plasma or apparently healthy control human plasma (CHP). SLE plasma decreased 27-hydroxylase message in THP-1 monocytes by 47 +/- 8% (p < 0.008) and in HAEC by 51 +/- 5.5% (n = 5, p < 0.001). THP-1 macrophages were incubated in 25% lupus plasma or CHP and cholesterol-loaded (50 microg ml(-1) acetylated low density lipoprotein). Lupus plasma more than doubled macrophage foam cell transformation (74 +/- 3% vs. 35 +/- 3% for CHP, n = 3, p < 0.001). Impaired cholesterol homeostasis in SLE provides further evidence of immune involvement in atherogenesis. Strategies to inhibit or reverse arterial cholesterol accumulation may benefit SLE patients.