As assessment of the surface charge of single resident and exudate macrophages and multinucleate giant cells.

The relative magnitude of the negative charge per unit area on the surface of resident and exudate macrophages as well as multinucleate giant cells was assessed by cytophotometric and ultrastructural techniques. The results indicate that the surface of resident macrophages possesses a higher negative charge per unit area than that of exudate macrophages or multinucleate giant cells. This may partly explain the relative ease of fusion of exudate macrophages into multinucleate giant cells since the electrostatic forces of repulsion are likely to be lower than between resident macrophages.