Macrophages from unstimulated, mineral oil and thioglycollate-stimulated mice: A comparative study of surface anionic sites and phagocytosis of 'old' red blood cells

The authors have studied the morphology and surface negative charge of macrophages from unstimulated (UM), thioglycollate-stimulated (TM), and mineral oil-stimulated (MM) mouse peritoneal cavities, and the ability of these macrophages to recognize and phagocytize 'old' red blood cells (RBC) from syngeneic mice. Morphologic differences between the various macrophage preparations were compared by both light and electron microscopy. The UM phagocytized much more 'old' RBC than the TM and MM (UM>MM>TM). On the other hand, the surface negative charge of MM was greater than that of UM, which in turn was greater than TM (MM>UM>TM). It thus appears that no direct correlation exists between the surface negative charge of the macrophages and their ability to recognize and phagocytize 'old' RBC.