title: The proinflammatory cytokine interleukin-12 occurs as a cell membrane-bound form on macrophages.
abstract: Phagocyte-derived interleukin-12 (IL-12) is a proinflammatory cytokine promoting cell-mediated immune responses in inflammatory and infectious disorders. Based on sequence homology of the p40 subunit with the interleukin-6 receptor it has been speculated that IL-12 could also exist as a membrane-bound form, but thus far only soluble (secreted) IL-12 has been identified. We have therefore analyzed human monocytic U937 and mouse P388D1 macrophages for membrane-bound IL-12 by flow cytometry. IL-12 is constitutively expressed on the cell surface of both cell lines. IL-12 cell surface staining is enhanced in response to stimulation with IFN-gamma plus LPS. IL-12 is also present in the supernatant of cultured P388D1 macrophages. Thus, in addition to a soluble form IL-12 occurs as a membrane-bound molecule on monocyte/macrophage cell lines.
authors.affiliation: Physiological Institute, University Zürich-Irchel, Switzerland.
authors.forename: X
authors.initials: X
authors.lastname: Fan
authors.forename: V
authors.initials: V
authors.lastname: Sibalic
authors.forename: E
authors.initials: E
authors.lastname: Niederer
authors.forename: R P
authors.initials: RP
authors.lastname: Wüthrich
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D015870:Gene Expression; D006801:Humans; D007111:Immunity, Cellular; D018836:Inflammation Mediators / Q000378:metabolism; D018664:Interleukin-12 / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D018836:Inflammation Mediators; D012333:RNA, Messenger; D018664:Interleukin-12