Mannose receptor dependent uptake of a ricin A chain--antibody conjugate by rat liver non-parenchymal cells.

Mannose receptor mediated uptake by the reticuloendothelial system has been suggested as an explanation for the rapid removal of ricin A chain antibody conjugates from the circulation after their administration. We have measured, in the rat, hepatic uptake of a ricin A chain antibody conjugate in vivo and its susceptibility to inhibition by a mannosylated protein and have measured uptake of the conjugate in vitro by rat parenchymal and non-parenchymal liver cells. The results indicate that rapid hepatic uptake of conjugate does occur in vivo; cultured non-parenchymal cells accumulate the conjugate to a much greater degree than cultured parenchymal cells and that mannose receptors appear to be involved in the process.