ANALYSIS OF FETAL-RAT LIVER USING MONOCLONAL-ANTIBODIES

Background: In previous studies, we developed several monoclonal antib odies (mAbs) against fetal and adult rat liver to analyze the hemopoie tic microenvironment of the fetal liver during the gestational period. In this study, we hat-e developed two new mAbs against fetal rat live r cells and have examined the characteristics at various gestational a ges of fetal liver and of adult liver. Methods: The characteristics of these monoclonal antibodies were demonstrated by examining several ti ssues using immunohistochemical staining and flow cytofluorometry. Res ults: Monoclonal antibodies HAM10 and HAM11 were developed against fet al rat liver cells. These reacted with the cytoplasm of fetal and adul t hepatocytes. HAM10 antigen expression was strong at approximately da y 18 of gestation in the active period of hemopoiesis in fetal rat liv er but was much lower in adult liver. HAM10 antigen expression also in creased in liver after partial hepatectomy and was reduced abruptly to a normal level thereafter. HAM11 antigen expression in fetal liver wa s weaker than that of HAM10 antigen expression. The degree of HAM11 an tigen expression increased as gestation proceeded, reaching a maximum in adult liver. Conclusions: Both HAM10 and HAM11 antigens may play a role in the morphogenesis of hepatocytes and in the hemopoietic microe nvironment for hemopoietic cells. Moreover, HAM10 antigen is may play a role in hepatocyte proliferation in the fetal liver, whereas HAM11 a ntigen may contribute to the maturation of fetal- to the adult-type he patocytes. (C) 1996 Wiley-Liss, Inc.