Our previous study demonstrated that reticuloendothelial system function can be monitored by
in vivo clearance of chondroitin sulfate iron colloid [Ishida, H.
et al. (1991):
J. Biochem. Biophys. Methods; Ishida, H.
et al (1992):
J. Biochem. Biophys. Methods; Tsujinaka, T.
et al. (1993):
JPEN]. In the present study hepatic clearance of radiolabeled chondroitin sulfate iron colloid (CS
59Fe) was investigated in detail. When administered intravenously, CS
59Fe was taken up by not only Kupffer cells but also liver endothelial cells and liver parenchymal cells. Radioactivity per 10
6 cells was highest in Kupffer cells. When binding of CS
59Fe to isolated liver cells was examined at 4°C, the association of CS
59Fe showed a good linearity on a double-reciprocal plot, giving
Nr (number of receptors) and
Kp (membrane-particle constant).
Nr was greatest of all for Kupffer cells. When CS
59Fe was pretreated with plasma, the
Nr increased and
Kp decreased in Kupffer cells and liver endothelial cells, whereas
Kp increased in liver parenchymal cells. However, no influence was found as a result of pre-treatment of CS
59Fe with fibronectin or heated plasma. The addition of mannan had no effect. This
in vitro chondroitin sulfate iron colloid binding assay may be useful to evaluate effects of various mediators on phagocytosis of hepatic cells.
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