Binding properties and expression of the Fc gamma receptors on guinea pig peritoneal macrophages treated with inhibitors of glycosylation.

The effect of inhibition of glycosylation in guinea pig peritoneal macrophages on interaction of their surface Fc gamma receptors with guinea pig and rabbit IgG was studied. The inhibitors used were tunicamycin and monensin. The cells treated with tunicamycin incorporated markedly less [3H]mannose, bound less peanut (PNA) and wheat germ (WGA) lectins and showed diminished ability of binding IgG in comparison with control cells. Treatment of the cells with monensin resulted in an increased incorporation of [3H]mannose, increased binding of PNA but a decreased binding of WGA. Monensin affected binding of guinea pig IgG2 and rabbit IgG to macrophages and had no effect on guinea pig IgG1 binding. Analysis of binding parameters showed that although the number of IgG-binding sites on treated cells was significantly lower, especially in the case of tunicamycin, the apparent association constants were 2-4 times higher than in control cells. The effect of tunicamycin and monensin on parameters of binding of guinea pig IgG2 or rabbit immunoglobulins was much more pronounced than in the case of binding guinea pig IgG1. The results showed that glycosylation modulates expression and IgG binding ability of the Fc gamma receptors on the surface of guinea pig peritoneal macrophages.