FIGURE 3.

C1q and MBL enhance ingestion of modified LDL by human monocytes and macrophages. Lipoproteins LDL, OxLDL, and AcLDL were labeled with DiI and incubated with phagocytes in the presence or absence of C1q/MBL at 37°C, for 30 min, and the MFI of ingestion was determined by flow cytometry. A, Representative histograms of monocyte ingestion of 10 μg protein/ml lipoprotein in the absence (solid line) or presence (dotted line) of 75 μg/ml C1q. Shaded histograms represent monocyte only control. B, Measurement of MFI of LDL, OxLDL, and AcLDL clearance by monocytes over a range of lipoprotein doses in the presence and absence of C1q (75 μg/ml). C, Measurement of MFI of LDL, OxLDL, and AcLDL clearance by HMDM over a range of lipoprotein doses in the presence and absence of MBL (10 μg/ml). D, Average fold modulation of MFI of clearance of LDL, OxLDL, and AcLDL (10 μg of protein/ml) by monocytes and HMDM by C1q (75 μg/ml) or MBL (10 μg/ml) compared with levels ingested in the absence of C1q or MBL. Data are the mean ± SD. *p < 0.05; **p <0.005, two-tailed Student t test (n > 3). E, Fold modulation of MFI of clearance of DiI-OxLDL (10 μg protein/ml) by monocytes in the presence of NHS or C1qD-MBLD with or without C1q (75 μg/ml) or MBL (10 μg/ml), compared with no serum control. Data are the mean ± SD. *p < 0.05, two-tailed Student t test (n = 3). Data in A–C are from single experiments and are representative of results obtained from different donors in at least three individual experiments.