Mechanism and clinical significance of soluble hepatic cell-surface receptors.

Transferrin receptors take up transferrin-iron complexes into hepatic cells. Although the receptor is not highly expressed in normal liver cells, malignant transformation of the cells increases its expression. As part of the expressed receptors are released into blood, a significant increase of serum receptors are observed in cases of hepatoma. Therefore, measurement of transferrin receptors in blood from patients with hepatoma may be useful for estimating the tumor burden and determinating therapeutic effects. Asialoglycoprotein receptors are expressed strongly in normal liver cells, whereas the expression is decreased in various chronic liver diseases and hepatoma. Although the active shedding of the receptors clearly occurs in vitro, as does that of the transferrin receptor, determination of the significance of these shed receptors in blood will require further studies.