title: The production and secretion of complement component C1q by human mast cells.
abstract: C1q is the initiation molecule of the classical pathway of the complement system and is produced by macrophages and immature dendritic cells. As mast cells share the same myeloid progenitor cells, we have studied whether also mast cells can produce and secrete C1q. Mast cells were generated in vitro from CD34+ progenitor cells from buffy coats or cord blood. Fully differentiated mast cells were shown by both RNA sequencing and qPCR to express C1QA, C1QB and C1QC. C1q produced by mast cells has a similar molecular make-up as serum C1q. Reconstituting C1q depleted serum with mast cell supernatant in haemolytic assays, indicated that C1q secreted by mast cells is functionally active. The level of C1q in supernatants produced under basal conditions was considerably enhanced upon stimulation with LPS, dexamethasone in combination with IFN- γ or via FcεRI triggering. Mast cells in human tissues stained positive for C1q in both healthy and in inflamed tissue. Moreover, mast cells in healthy and diseased skin appear to be the predominant C1q positive cells. Together, our data reveal that mast cells are able to produce and secrete functional active C1q and indicate mast cells as a local source of C1q in human tissue.
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Rosanne A
authors.initials: RA
authors.lastname: van Schaarenburg
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands; The Feinstein Institute for Medical Research, New York City, United States.
authors.forename: Jolien
authors.initials: J
authors.lastname: Suurmond
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Kim L L
authors.initials: KL
authors.lastname: Habets
authors.affiliation: Department of Immunopathology, Sanquin Research, Amsterdam, The Netherlands.
authors.forename: Mieke C
authors.initials: MC
authors.lastname: Brouwer
authors.affiliation: Department of Immunopathology, Sanquin Research, Amsterdam, The Netherlands.
authors.forename: Diana
authors.initials: D
authors.lastname: Wouters
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Fina A S
authors.initials: FA
authors.lastname: Kurreeman
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Tom W J
authors.initials: TW
authors.lastname: Huizinga
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: René E M
authors.initials: RE
authors.lastname: Toes
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: L.A.Trouw@lumc.nl.
authors.forename: Leendert A
authors.initials: LA
authors.lastname: Trouw
mesh_terms: D015153:Blotting, Western; D002469:Cell Separation; D002478:Cells, Cultured; D015922:Complement C1q / Q000096:biosynthesis* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism
chemical_list: D015922:Complement C1q
keywords: C1q; Complement; FcεRI; Innate immunity; Mast cells