Binding of ssDNA-antibody complexes to thioglycollate-induced mouse peritoneal macrophages in the presence of serum

Factors involved in macrophage: immune complex binding

The interaction of the immune complex (IC) composed of DNA and monoclonal anti-DNA antibody with thioglycollate-stimulated mouse peritoneal macrophages was investigated. The immune complex: macrophage interaction was shown to be highly time and temperature dependent; at 37 degrees C it proceeds faster than at 0 degrees C, although there is higher overall binding of IC to macrophages at 0 degrees C. The maximum bound IC detected was at a DNA/antibody ratio of 6.2ng/ml to 7.3 micrograms/ml. Higher densities of either DNA or antibody inhibited IC: phagocyte interaction. Binding of the IC to macrophages is through cell surface Fc receptors and is enhanced in the presence of 40 mg/ml albumin. Fresh human and mouse sera at the concentration of 10 percent, inhibited the IC binding to mouse peritoneal macrophages. Macrophage receptors for IC are not saturated even after 60 minutes. Addition of either chloroquine or cytochalasin B, resulted in increased binding of IC to macrophages.