title: Production of IL-12 by human monocyte-derived dendritic cells is optimal when the stimulus is given at the onset of maturation, and is further enhanced by IL-4.
abstract: Dendritic cells produce IL-12 both in response to microbial stimuli and to T cells, and can thus skew T cell reactivity toward a Th1 pattern. We investigated the capacity of dendritic cells to elaborate IL-12 with special regard to their state of maturation, different maturation stimuli, and its regulation by Th1/Th2-influencing cytokines. Monocyte-derived dendritic cells were generated with GM-CSF and IL-4 for 7 days, followed by another 3 days +/- monocyte-conditioned media, yielding mature (CD83(+)/dendritic cell-lysosome-associated membrane glycoprotein(+)) and immature (CD83(-)/dendritic cell-lysosome-associated membrane glycoprotein(-)) dendritic cells. These dendritic cells were stimulated for another 48 h, and IL-12 p70 was measured by ELISA. We found the following: 1) Immature dendritic cells stimulated with CD154/CD40 ligand or bacteria (both of which concurrently also induced maturation) secreted always more IL-12 than already mature dendritic cells. Mature CD154-stimulated dendritic cells still made significant levels (up to 4 ng/ml). 2) Terminally mature skin-derived dendritic cells did not make any IL-12 in response to these stimuli. 3) Appropriate maturation stimuli are required for IL-12 production: CD40 ligation and bacteria are sufficient; monocyte-conditioned media are not. 4) Unexpectedly, IL-4 markedly increased the amount of IL-12 produced by both immature and mature dendritic cells, when present during stimulation. 5) IL-10 inhibited the production of IL-12. Our results, employing a cell culture system that is now being widely used in immunotherapy, extend prior data that IL-12 is produced most abundantly by dendritic cells that are beginning to respond to maturation stimuli. Surprisingly, IL-12 is only elicited by select maturation stimuli, but can be markedly enhanced by the addition of the Th2 cytokine, IL-4.
authors: Department of Dermatology, University of Innsbruck, Innsbruck, Austria.
authors: S
authors: S
authors: Ebner
authors: G
authors: G
authors: Ratzinger
authors: B
authors: B
authors: Krösbacher
authors: M
authors: M
authors: Schmuth
authors: A
authors: A
authors: Weiss
authors: D
authors: D
authors: Reider
authors: R A
authors: RA
authors: Kroczek
authors: M
authors: M
authors: Herold
authors: C
authors: C
authors: Heufler
authors: P
authors: P
authors: Fritsch
authors: N
authors: N
authors: Romani
mesh_terms: D000276:Adjuvants, Immunologic / Q000502:physiology*; D000818:Animals; D019013:CD40 Antigens / Q000276:immunology / Q000378:metabolism; D023201:CD40 Ligand / Q000096:biosynthesis / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D005434:Flow Cytometry; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000494:pharmacology; D018664:Interleukin-12 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D015847:Interleukin-4 / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000276:immunology / Q000378:metabolism; D051379:Mice; D009000:Monocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D012867:Skin / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D013211:Staphylococcus aureus / Q000276:immunology; D014158:Transcription, Genetic / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D019013:CD40 Antigens; D017077:Culture Media, Conditioned; D006131:Growth Inhibitors; D016753:Interleukin-10; D023201:CD40 Ligand; D018664:Interleukin-12; D015847:Interleukin-4; D007371:Interferon-gamma