title: Cell culture plastics with immobilized interleukin-4 for monocyte differentiation.
abstract: Standard cell culture plastic was surface modified by passive adsorption or covalent attachment of interleukin (IL)-4 and investigated for its ability to induce differentiation of human monocytes into mature dendritic cells, a process dose-dependently regulated by IL-4. Covalent attachment of IL-4 proceeded via anthraquinone photochemistry to introduce amine functionalities at the surface followed by coupling of IL-4 through a bifunctional amine-reactive linker. X-ray photoelectron spectroscopy showed that undesirable multilayer formation of the photoactive compound could be avoided by reaction in water instead of phosphate-buffered saline. Passively adsorbed IL-4 was observed to induce differentiation to dendritic cells, but analysis of cell culture supernatants revealed that leakage of IL-4 into solution could account for the differentiation observed. Covalent attachment resulted in bound IL-4 at similar concentrations to the passive adsorption process, as measured by enzyme-linked immunosorbent assays, and the bound IL-4 did not leak into solution to any measurable extent during cell culture. However, covalently bound IL-4 was incapable of inducing monocyte differentiation. This may be caused by IL-4 denaturation or improper epitope presentation induced by the immobilization process, or by biological irresponsiveness of monocytes to IL-4 in immobilized formats.
authors.affiliation: Department of Micro- and Nanotechnology, Technical University of Denmark, DTU-Nanotech, DK-2800 Kongens Lyngby, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Hansen
authors.forename: Gertrud M
authors.initials: GM
authors.lastname: Hjortø
authors.forename: Ozcan
authors.initials: O
authors.lastname: Met
authors.forename: Mogens H
authors.initials: MH
authors.lastname: Jakobsen
authors.forename: Inge M
authors.initials: IM
authors.lastname: Svane
authors.forename: Niels B
authors.initials: NB
authors.lastname: Larsen
mesh_terms: D000327:Adsorption / Q000187:drug effects; D000880:Anthraquinones / Q000737:chemistry / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods*; D002454:Cell Differentiation / Q000187:drug effects*; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D055767:Immobilized Proteins / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D009000:Monocytes / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D010969:Plastics / Q000494:pharmacology*; D012996:Solutions; D013499:Surface Properties / Q000187:drug effects; D014227:Triazines / Q000737:chemistry / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000880:Anthraquinones; D055767:Immobilized Proteins; D010969:Plastics; D012996:Solutions; D014227:Triazines; D015847:Interleukin-4; C019309:cyanuric chloride