Secretion of polyalbumin receptors in vitro.
The nature of hepatitis B surface antigen (HBsAg)-associated receptors for polymerized human serum albumin (pHSA-R) and their relationship to hepatitis B e antigen (HBeAg) and human serum proteins have not been defined. We studied by radioimmunoassay and by electron microscopy HBsAg-associated pHSA-R secreted in vitro by a human hepatocellular carcinoma cell line (PLC/PRF/5) and by mouse 3T3 fibroblasts after transfection with cloned hepatitis B virus (HBV) DNA (4.10 cells). PLC/PRF/5 cells expressed only HBsAg, whereas 4.10 cells secreted also HBeAg. There was no significant difference in the production of HBsAg, HBeAg, and pHSA-R when the cells were cultured in the presence or absence of fetal calf serum. Secretion of pHSA-R by the two cell lines for a given amount of HBsAg was equal irrespective of the presence or absence of HBeAg. Supernatants from both cell lines grown in serum-free medium did not contain any Clq or albumin when tested by immunodiffusion. The ability of a transfected mouse cell line to produce HBsAg with pHSA-R activity strongly suggests that pHSA-R is coded by the HBV genome and does not depend on the presence of human serum proteins. In addition, our findings fail to demonstrate any correlation between HBeAg production and pHSA-R.
Gilja
B K
BK
Kasambalides
E J
EJ
Bressler
R S
RS
Thung
S N
SN
Gerber
M A
MA
D000818:Animals; D006528:Carcinoma, Hepatocellular; D002460:Cell Line; D002846:Chromatography, Affinity; D006511:Hepatitis B Antigens / Q000032:analysis*; D006514:Hepatitis B Surface Antigens / Q000032:analysis*; D006513:Hepatitis B e Antigens / Q000032:analysis*; D006801:Humans; D066298:In Vitro Techniques; D008113:Liver Neoplasms; D051379:Mice; D008854:Microscopy, Electron; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface / Q000032:analysis*; D012709:Serum Albumin / Q000032:analysis*; D000075462:Serum Albumin, Human
D006511:Hepatitis B Antigens; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface; D012709:Serum Albumin; C032137:polyalbumin; D000075462:Serum Albumin, Human