Fc- and complement receptor-dependent degradation of soluble immune complexes and stable immunoglobulin aggregates by guinea pig monocytes, peritoneal macrophages, and Kupffer cells

Abstract

The degradation of soluble immune complexes (ICx) and stable soluble immunoglobulin aggregates was studied in vitro. To obtain insight into the capacity of phagocytes from different organs to degrade soluble ICx we studied monocytes, peritoneal macrophages, and Kupffer cells. Peritoneal macrophages and Kupffer cells degrade similar amounts of aggregated guinea pig IgG2 (AIgG) and ICx per cell. Monocytes were at least ten times less effective than peritoneal macrophages and Kupffer cells. The presence of normal guinea pig serum as a source of complement enhanced the degradation of ICx and AIgG by peritoneal macrophages and monocytes. There was, however, a diminished degradation of ICx and AIgG by freshly isolated Kupffer cells in the presence of complement. After culturing of the Kupffer cells for 40 hours, there was an increase in the density of C3b receptors and a concomitant reversal of inhibition of AIgG degradation in the presence of complement. It can be concluded from the present experiments that the capacities of peritoneal macrophages and Kupffer cells to degrade soluble ICx and AIgG are comparable and that monocytes are much less active than peritoneal macrophages and Kupffer cells.