Figure 2.

Degradation of [¹²⁵I]LDL by hMDMs and MPMs after modification by MPO-generated chlorinating and nitrating intermediates. [¹²⁵I]LDL (0.2 mg/mL) was incubated with isolated human MPO (30 nM), glucose (100 μM), and glucose oxidase (20 ng/mL) in the presence of the indicated additions in sodium phosphate buffer (50 mM, pH 7.0) supplemented with DTPA (100 μM) overnight at 37°C, as described in Methods. Under these conditions, a constant flux of H₂O₂ (0.18 μM/min) is generated by the GGOx system. Reactions were stopped by addition of BHT (40 μM) and catalase (300 nM), and then ¹²⁵I-labeled lipoproteins (5 μg/mL) were incubated with either hMDMs (a) or thioglycollate-elicited MPMs (b) at 37°C for 5 hours in the appropriate media containing additional catalase (300 nM) and BHT (20 μM). Cellular uptake of lipoproteins was subsequently determined as described in Methods. When indicated, Cl^– (100 mM) or NO₂^– (500 μM) were added during LDL modification by MPO. Data represent the mean ± SD of triplicate determinations. Similar results were observed in 3 independent experiments. *P < 0.001 for comparison vs. LDL modified in the presence of MPO and an H₂O₂-generating system (LDL/MPO/GGOx).