title: Secretion of insulin-like growth factor binding protein-1 from individual hepatocytes.
abstract: The reverse hemolytic plaque assay (RHPA) uses complement-mediated red blood cell lysis to detect peptide secretion by individual cells. Initially, the RHPA was used to study the function of neurons and B lymphocytes. More recently, the RHPA has been adapted to measure hormone release from individual pituitary, parathyroid, luteal, and pancreatic islet cells. We have applied this technique to detect insulin-like growth factor binding protein-1 (IGFBP-1) secretion by a human hepatoma cell line (HepG2). We proposed that the technique of RHPA could be used to study peptide release from single hepatocytes in various defined conditions. Our goal was the study of the kinetics of IGFBP-1 secretion from hepatoma cells and rat hepatocytes and to determine the heterogeneity of the cell population regarding the secretion of IGFBP-1. To evaluate the optimal conditions of IGFBP-1 secretion by hepatoma cells and rat hepatocytes and to evaluate the influence of cell dispersion on hepatocyte's behavior, we evaluated three techniques of cell dispersion: trypsin digestion, collagenase digestion, and mechanical dispersion. We tested cell viability, determined the percentage of secreting cells versus non-secreting cells, and measured mean plaque area which is a function of the amount of IGFBP-1 secreted by an individual cell. We determined the optimal IGFBP-1 antibody dilution for the detection of secreted IGFBP-1 by hepatocytes, evaluated the initiation of IGFBP-1 secretion from cultured cells, and quantified time-dependent IGFBP-1 secretion. In addition to demonstrating the feasibility of measuring IGFBP-1 from a cultured cell line, we measured IGFBP-1 release from freshly dispersed rat hepatocytes.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905.
authors.forename: G
authors.initials: G
authors.lastname: Eghbali-Fatourechi
authors.forename: C A
authors.initials: CA
authors.lastname: Conover
authors.forename: G C
authors.initials: GC
authors.lastname: Sieck
authors.forename: G J
authors.initials: GJ
authors.lastname: Gores
authors.forename: L A
authors.initials: LA
authors.lastname: Fitzpatrick
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism*; D002469:Cell Separation; D002470:Cell Survival; D002478:Cells, Cultured; D006131:Growth Inhibitors / Q000378:metabolism*; D006462:Hemolytic Plaque Technique; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D051381:Rats; D012756:Sheep; D013002:Somatomedins / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D002352:Carrier Proteins; D006131:Growth Inhibitors; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins