Figure 4.

The capacity of monocyte-derived macrophages to produce H₂O₂ parallels their expression of CD36. A: Human monocytes/macrophages, cultured for 1 to 14 days in Teflon beakers, were added to wells coated with 2.5 μg of collagen IV overlayed with 2 μg of fibrillar Aβ 1-42 (open triangle), fibrillar Aβ 25-35 (filled square), or Aβ 35-25 (open circle) and incubated for 3 hours. H₂O₂ production was determined using the Molecular Probes Hydrogen Peroxide Assay Kit as described in Materials and Methods. Data presented are mean values ± SEM above background (collagen IV alone) for six experiments, each done in triplicate. B: H₂O₂ production by human monocyte-derived macrophages cultured for 5 days in Teflon beakers. Cells were incubated as in A above in wells containing collagen IV alone or collagen IV and 2 μg of fAβ 1-42 or 2 μg of Aβ 42-1. Data presented are mean values ± SEM above background (collagen IV alone) for three experiments each done in triplicate. *, Indicates values significantly different (P < 0.05) from control (open circles), using Student’s test. C: Summary of FACS analyses of CD36 expression on the surfaces of human monocytes/macrophages maintained in Teflon beakers and assayed at the times indicated as described in Materials and Methods. H₂O₂ production and CD36 expression were both maximal in cells cultured for 5 days.