title: IL-6 and IL-1 enhance the accessory activity of human blood monocytes during differentiation to macrophages.
abstract: The role of IL-6 and IL-1 in the regulation of accessory activity and differentiation in the human monocyte/macrophage (Mo/Mph) system was investigated. IL-6 combined with IL-1 had a strong effect on the accessory activity of Mo-derived cells dependent on their state of differentiation in vitro. Fresh Mo prepared from peripheral blood differentiated into potent accessory cells in vitro within 24 h in the absence of exogenous triggers in serum-containing and serum-free medium. Mo cultured for 2 days in the presence of the cytokines IL-6 and IL-1 did not significantly increase their spontaneous accessory activity. However, the simultaneous addition of antibodies against IL-6 and IL-1 to accessory Mo cultures significantly diminished their T cell stimulatory capacity. These findings suggest an important positive feedback role of IL-6 and IL-1, secreted by Mo at this early state of differentiation. In marked contrast, untreated mature Mph generated in vitro from Mo exhibited a low spontaneous accessory potency. However, when these cells were subjected to IL-6 and/or IL-1, we observed a strong dose dependent increase in their potency to stimulate a T cell response. Parameters indicating the differentiation of Mo to Mph, such as acid phosphatase and 5' nucleotidase, were not influenced by the addition of IL-1, IL-6, or a mixture of both and confirmed the presence of mature Mph after 6 days of culture. Based on these observations, we conclude that the monocyte-derived cytokines IL-6 and IL-1 not only directly act on T cells but may also function as a signal for accessory activity during Mo/Mph differentiation.
authors.affiliation: Department of Immunology, Georg-August-Universität Göttingen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ruppert
authors.forename: J H
authors.initials: JH
authors.lastname: Peters
mesh_terms: D015720:5'-Nucleotidase / Q000378:metabolism; D000135:Acid Phosphatase / Q000378:metabolism; D000938:Antigen-Presenting Cells / Q000276:immunology*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology*; D008264:Macrophages / Q000201:enzymology / Q000276:immunology*; D009000:Monocytes / Q000166:cytology* / Q000201:enzymology
chemical_list: D007375:Interleukin-1; D015850:Interleukin-6; D000135:Acid Phosphatase; D015720:5'-Nucleotidase