Figure 7.
Heme modulates phagocytosis and killing by AM. Rat AMs (2 × 106/mL) were cultured in the absence or presence of heme (3–300 μM) for different periods of time. (a), (b) Following the incubation with heme for 10 min (a) or 24 h (b), IgG-SRBCs were added and cultures were incubated for an additional 90 min at 37°C. Phagocytosis was assessed by a colorimetric assay as described in Section 2. (c) Following the incubation with heme (3–300 μM) for 10 min, cells were infected with opsonized K. pneumoniae for 30 min to allow phagocytosis to occur. The intensity of the absorbance at 595 nm is directly proportional to the number of intracellular bacteria associated with the macrophages. Results are expressed as mean ± S.D. of three independent experiments. RBC, macrophage exposed to unopsonized RBC. *P < 0.05 compared with control group.