Effect of HO-1–deficient child's LDL on endothelial cells and on electrophoretic mobility.

HO-1–deficient child's LDL is cytotoxic to endothelial cells and has increased electrophoretic mobility accompanied by oxidation of plasma Hb. (A) Exposure of endothelial cells to the child's LDL. Endothelial cells from healthy subjects were treated with native LDL (first bar), LDL from patient (second bar), LDL from healthy individuals' plasma samples that were handled similarly to those from the patient with HO-1 deficiency (third bar), or LDL from metHb-pretreated plasma (fourth bar). After a 4-hour incubation with LDL (200 μg/mL protein), MTT assays were performed. Results represent the percentage of specific cytotoxicity (mean ± SE) of 2 experiments done in triplicate. (B) Spectral analysis of plasma-Hb. Plasma samples were diluted with saline and scanned with the use of diluted Hb-free plasma as blank. Solid line represents the wavelength scan of the child's plasma; also represented are wavelength scans of diluted plasma from healthy subjects containing 2.5 μM ferroHb (long dash) or 2.5 μM of metHb (dash-dot). (C) Electrophoretic mobility of the child's LDL. Native LDL (3 μg) (lanes 1 and 6); oxidatively modified LDL (lane 2); patient's LDL (lane 3); and LDL from plasma containing 20 μM ferroHb (fourth lane) or 20 μM metHb (lane 5) were electrophoresed on agarose gel.