Figure 1.

Degradation of [¹²⁵I]LDL by hMDMs and MPMs after modification by activated human monocytes. Isolated human monocytes (10⁶/mL) were incubated at 37°C in HBSS supplemented with DTPA (100 μM), [¹²⁵I]LDL (0.2 mg/mL), and NO₂^– (500 μM). Monocytes were activated with phorbol ester (200 nM) and maintained in suspensions by intermittent inversion (complete system) for 8 hours. Additions or deletions to the complete system were as indicated. Reactions were stopped by addition of BHT (40 μM) and catalase (300 nM); the cells were pelleted; 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. The final concentrations of additions to the complete system were catalase (300 nM) and 3-aminotriazole (1 mM). Data represent the mean ± SD of 3 separate experiments. *P < 0.001 for complete system vs. complete system – NO₂^–. Atz, 3-aminotriazole; Mono, human peripheral blood monocyte.