title: Extracellular ATP and TNF-alpha synergize in the activation and maturation of human dendritic cells.
abstract: Extracellular ATP mediates numerous biological activities by interacting with plasma membrane P2 purinergic receptors. Recently, P2 receptors have been described on dendritic cells (DC), but their functional role remains unclear. Proposed functions include improved Ag presentation, cytokine production, chemotaxis, and induction of apoptosis. We investigated the effects of ATP and of other P2 receptor agonists on endocytosis, phenotype, IL-12 secretion, and T cell stimulatory capacity of human monocyte-derived DC. We found that in the presence of extracellular ATP, DC transiently increase their endocytotic activity. Subsequently, DC up-regulate CD86, CD54, and MHC-II; secrete IL-12; and exhibit an improved stimulatory capacity for allogeneic T cells. These effects were more pronounced when chemically modified ATP derivatives with agonistic activity on P2 receptors, which are resistent to degradation by ectonucleotidases, were applied. Furthermore, ATP and TNF-alpha synergized in the activation of DC. Stimulated with a combination of ATP and TNF-alpha, DC expressed the maturation marker CD83, secreted large amounts of IL-12, and were potent stimulators of T cells. In the presence of the P2 receptor antagonist suramin, the effects of ATP were completely abolished. Our results suggest that extracellular ATP may play an important immunomodulatory role by activating DC and by skewing the immune reaction toward a Th1 response through the induction of IL-12 secretion.
authors.affiliation: Division of Clinical Pharmacology, Department of Medicine, Ludwig-Maximilians-University of Munich, Munich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schnurr
authors.forename: F
authors.initials: F
authors.lastname: Then
authors.forename: P
authors.initials: P
authors.lastname: Galambos
authors.forename: C
authors.initials: C
authors.lastname: Scholz
authors.forename: B
authors.initials: B
authors.lastname: Siegmund
authors.forename: S
authors.initials: S
authors.lastname: Endres
authors.forename: A
authors.initials: A
authors.lastname: Eigler
mesh_terms: D000255:Adenosine Triphosphate / Q000276:immunology / Q000502:physiology*; D000276:Adjuvants, Immunologic / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D002454:Cell Differentiation / Q000276:immunology; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D004357:Drug Synergism; D004705:Endocytosis / Q000276:immunology; D005110:Extracellular Space / Q000276:immunology / Q000502:physiology*; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis; D006801:Humans; D018664:Interleukin-12 / Q000378:metabolism; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D013601:T-Lymphocytes / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D015854:Up-Regulation / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D015815:Cell Adhesion Molecules; D000949:Histocompatibility Antigens Class II; D014409:Tumor Necrosis Factor-alpha; D018664:Interleukin-12; D000255:Adenosine Triphosphate