Interaction of macrophages with "old" red blood cells from syngeneic mice in vitro and the independence of the recognition process on macrophage Fc receptors.

The interaction between peritoneal macrophages and "old" red blood cells (RBC) from syngeneic mice was studied in vitro. It seems that this interaction is not mediated directly via Fc receptors on the macrophage. (1) 2-deoxy-D-glucose did not inhibit the phagocytosis of "old" RBC, but did inhibit the phagocytosis of IgG-coated sheep RBC (SRBC). (2) Immobilization of Fc receptors by plating macrophages on coverslips coated with bovine serum albumin: anti-bovine serum albumin (BSA: anti-BSA) complexes had no effect on the phagocytosis of "old" RBC, but inhibited the phagocytosis of IgG-coated SRBC. The interaction between mouse macrophages and "old" RBC is temperature dependent. At 4 degrees C and 22 degrees C "old" RBC attach to macrophages but are not phagocytized; at 37 degrees C phagocytosis occurs. Fetal calf serum (FCS) is required for optimal phagocytosis. Sialic acid residues on the macrophage surface do not play a role in this recognition and phagocytosis process, as neuraminidase treatment of macrophages did not affect the interaction.