A histochemical study about the involvement of rat liver cells in the uptake of heterologous immune complexes from the circulation.

Intravenously injected immune complexes (ICx) composed of bovine serum albumin (BSA) and rabbit anti-BSA were taken up by the liver. Insoluble complexes, made in antibody excess, were rapidly taken up by Kupffer cells and were metabolized within 24 h. Soluble complexes, made in antigen excess, were only partly taken up by Kupffer cells. In addition these complexes were bound, taken up and metabolized by endothelial cells. Until 2 h after injection soluble complexes could also be observed along the microvilli of hepatocytes. No signs of endocytosis in hepatocytes could be observed. It is concluded, that ICx can be taken up by Kupffer cells as well as by endothelial cells. The physical state of the complexes, soluble or insoluble, determines the cell type in which uptake occurs.