A temperature-dependent inhibitory activity of serum on the capacity of Saccharomyces cerevisiae-derived hepatitis B surface antigen to bind to monocytes.
Hepatitis B surface antigen, when produced in yeast (rHBsAg), is capable of binding to cells that express the lipopolysaccharide coreceptor CD14. This interaction is enhanced by a serum protein, the lipopolysaccharide binding protein (LBP). Here we report that most of the rHBsAg particles that attached to monocytes at 0 degrees C, were not endocytosed but were released back into the serum-containing binding buffer at 37 degrees C. Additionally, serum-dependent binding at 37 degrees C was weak when compared to the serum-dependent attachment at 0 degrees C. Pre-incubation at 37 degrees C of cells together with serum did not abolish binding of freshly added rHBsAg at 0 degrees C. However, pre-incubation of rHBsAg with serum at 37 degrees C reduced attachment to cells following incubation at 0 degrees C. Soluble CD14 and LBP, two serum proteins which can act as phospholipid transfer molecules, were shown not to be responsible for the inhibitory effect. Pre-incubation at 37 degrees C of rHBsAg in serum-free hepatoma cell line-conditioned media resulted in a pronounced reduction in subsequent binding to cells at 0 degrees C. These observations suggest that the temperature-dependent inhibitory effect is caused by serum factors that are probably secreted by hepatocytes.
Vanlandschoot
P
P
Center for Vaccinology, Department of Clinical Biology, Microbiology and Immunology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium. Peter.Vanlandschoot@UGent.be
Van Houtte
F
F
Roobrouck
A
A
Stelter
F
F
Gavilanes
F
F
Leroux-Roels
G
G
D000209:Acute-Phase Proteins; D000818:Animals; D016466:CHO Cells; D002352:Carrier Proteins; D045744:Cell Line, Tumor; D006224:Cricetinae; D017077:Culture Media, Conditioned; D006514:Hepatitis B Surface Antigens / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D006801:Humans; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D051379:Mice; D009000:Monocytes / Q000276:immunology*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D044967:Serum / Q000276:immunology*; D013696:Temperature; D013997:Time Factors; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D017077:Culture Media, Conditioned; D006514:Hepatitis B Surface Antigens; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D000099231:Lipopolysaccharide-Binding Protein