title: Human monocytoid cells as a model to study Toll-like receptor-mediated activation.
abstract: THP-1 2A9, a subclone of the monocytoid cell line THP-1 and known to be exquisitely sensitive to LPS, was tested for TNF production following triggering by excess doses of TLR ligands. TLR2, TLR4 and TLR5 agonists, but neither TLR3 nor TLR9 agonists, induced TNF production. When used at lower concentrations, priming by calcitriol strongly influenced the sensitivity of cells to LPS and different TLR2 triggers (lipoteichoic acid (LTA), trispalmitoyl-cysteyl-seryl-lysyl-lysyl-lysyl-lysine (Pam3Cys) and peptidoglycan (PGN)). Priming by calcitriol failed to modulate TLR2 and TLR4 mRNA and cell surface expression of these receptors. TNF signals elicited by TLR2 agonists were blocked by the TLR-specific antibody 2392. CD14-specific antibodies showed variable effects. CD14-specific antibodies inhibited TNF induction by LTA. High concentrations partially inhibited TNF induction by Pam3Cys. The same antibodies failed to inhibit TNF induction by PGN. Thus, THP-1 2A9 cells respond by TNF production to some, but not all TLR agonists, and the wide variety of putative TLR2 agonists interact to variable degrees also with other cell-surface-expressed binding sites such as CD14. THP-1 2A9 cells might provide a model by which to investigate in more detail the interaction of pathogen-associated molecular patterns and monocytoid cell-surface-expressed pattern recognition receptors.
authors.affiliation: Institute of Veterinary Virology, University of Bern, Bern, Switzerland.
authors.forename: Katharina A
authors.initials: KA
authors.lastname: Remer
authors.forename: Marija
authors.initials: M
authors.lastname: Brcic
authors.forename: Kay-Sara
authors.initials: KS
authors.lastname: Sauter
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Jungi
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002117:Calcitriol / Q000494:pharmacology; D002460:Cell Line; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D005408:Flagellin / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008074:Lipoproteins / Q000494:pharmacology; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D010457:Peptidoglycan / Q000494:pharmacology; D011070:Poly I-C / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013682:Teichoic Acids / Q000494:pharmacology; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000235:genetics / Q000276:immunology; D051196:Toll-Like Receptor 3 / Q000819:agonists; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000235:genetics / Q000276:immunology; D051198:Toll-Like Receptor 5 / Q000819:agonists; D051217:Toll-Like Receptor 9 / Q000819:agonists; D051193:Toll-Like Receptors / Q000819:agonists / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008074:Lipoproteins; D010457:Peptidoglycan; D012333:RNA, Messenger; C495342:TLR2 protein, human; C495344:TLR3 protein, human; C495345:TLR4 protein, human; C495346:TLR5 protein, human; C495371:TLR9 protein, human; D013682:Teichoic Acids; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051198:Toll-Like Receptor 5; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; C482199:lipopolysaccharide, E coli O55-B5; D005408:Flagellin; C009900:lipoteichoic acid; D007371:Interferon-gamma; C069172:2,3-bis(palmitoyloxy)-2-propyl-1-palmitoylcysteine; D002117:Calcitriol; D003545:Cysteine; D011070:Poly I-C