THE COMPLEMENT-MEDIATED BUT NOT MANNOSE RECEPTOR-MEDIATED PHAGOCYTOSIS IS INVOLVED IN THE HEPATIC-UPTAKE OF CETYLMANNOSIDE-MODIFIED LIPOSOMES IN-SITU

In the elimination of injected liposomes in vivo, it is considered tha t several serum components play an important role on hepatic uptake of them. This study was conducted to clarify the hepatic uptake mechanis m of cetylmannoside (Man)-modified multilamellar vesicles (Man-MLV) us ing perfused rat liver. In the presence of serum, Man-MLV was taken up by the liver depending on the serum concentration, and it showed an a pproximately two-fold higher accumulation than MLV without any surface modifications (PC-MLV). These heptic uptakes of liposomes were obviou sly inhibited by preheating the serum at 56-degrees-C for thirty minut es or by the treatment with anti-rat C3 antiserum. Further, SDS-PAGE f ollowed by immunoblot analysis showed the deposition of iC3b on the op sonized Man-MLV. These results obtained in the present study suggested that hepatic uptake of Man-MLV was mainly mediated by complement rece ptor rather than mannose receptor on Kupffer cells in vivo.