Surface Charge and Ultrastructure of the Cell Surface of Resident and Thioglycolate-elicited Mouse Peritoneal Macrophages

The cell surface of resident and thioglycolate-elicited mouse peritoneal macrophages was analysed using cell electrophoresis, ultrastructural cytochemistry and freeze-fracture. Both macrophages have a negative surface charge as evaluated by the binding of cationic particles (colloidal iron hydroxide and cationized ferritin) to the cell surface and determination of the cellular electrophoretic mobility (EPM). Elicited macrophages showed a more regular and intense binding of colloidal iron particles at pH 1.8 to their cell surfaces than resident macrophages. No differences were observed in the binding of cationized ferritin particles at pH 7.2 to the cell surface of resident and elicited macrophages. Both macrophages had the same mean EPM. Neuraminidase treatment of the cells did not interfere with the binding of cationic particles to the cell surface and with the EPM of the cells. With the freeze-fracture technique no special array of intramembranous particles was observed in the plasma membrane of the macrophages. Differences in the distribution of intramembranous particles in the P and E faces of the plasma membrane were observed between resident and elicited macrophages.