Surface charge of resident, elicited, and activated mouse peritoneal macrophages.

The surface charge of resident, thioglycollate-elicited, and Trypanosoma cruzi-activated mouse peritoneal macrophages was analyzed using cell electrophoresis. All macrophages had a net negative surface charge. Activated macrophages had a lower zeta potential and a higher isoelectrophoretic point than resident and elicited macrophages. The populations of resident, elicited, and activated macrophages were heterogeneous in terms of surface charge. The analysis of the effect of the pH of the solution in which the macrophages were suspended on their cellular electrophoretic mobility (EPM) indicated that their surface contained both positively and negatively charged dissociating groups. The contribution of sialic acid residues to the surface charge was determined by analyzing the effect of neuraminidase treatment on the EPM of the cells. Activated macrophages possessed more sialic acid residues exposed on their surface, and sensitive to the neuraminidase from Clostridium perfringens, than resident and elicited macrophages. Treatment of the cells with the neuraminidase from Vibrio cholerae, however, reduced the surface charge of all macrophages in about the same extent. Macrophages had their mean EPM reduced when incubated in the presence of Ca++, suggesting that some cell surface anionogenic sites have Ca++-binding capacity.