title: IgE and IL-33-mediated triggering of human basophils inhibits TLR4-induced monocyte activation.
abstract: Basophils are circulating granulocytes, best known as effector cells in allergic reactions. Recent studies in mice suggest that they might also participate in the suppression of chronic inflammation. The aim of this study was to assess the ability of purified human basophils to modulate monocyte responses upon IL-33 and IgE triggering. Activation of human basophils with IL-33 induced the production of IL-4 and the release of histamine, and enhanced their IgE-mediated activation. In addition, basophils triggered with IL-33 and anti-IgE significantly suppressed the LPS-induced production of the proinflammatory cytokine TNF-α and the upregulation of the costimulatory molecule CD80 by monocytes. These effects were mainly explained by the release of histamine, as they could be inhibited by the histamine receptor 2 antagonist ranitidine, with a smaller contribution of IL-4. In contrast, basophil-derived IL-4 and histamine had opposing effects on the expression of the inhibitory Fc γ receptor IIb and the production of IL-10 by monocytes. Our data show that basophils can influence monocyte activation and suggest a previously unrecognized role for human basophils in the modulation of monocyte-mediated immune responses, through the balanced secretion of histamine and IL-4.
authors: Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands; Department of Translational Medical Sciences and Center for Basic and Clinical Immunology Research (CISI), University of Naples Federico II, Naples, Italy.
authors: Felice
authors: F
authors: Rivellese
authors: Jolien
authors: J
authors: Suurmond
authors: Amato
authors: A
authors: de Paulis
authors: Gianni
authors: G
authors: Marone
authors: Tom W J
authors: TW
authors: Huizinga
authors: René E M
authors: RE
authors: Toes
mesh_terms: D001491:Basophils / Q000276:immunology*; D002469:Cell Separation; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D000067596:Interleukin-33; D007378:Interleukins / Q000276:immunology*; D009000:Monocytes / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology
chemical_list: D016207:Cytokines; C506536:IL33 protein, human; D000067596:Interleukin-33; D007378:Interleukins; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D007073:Immunoglobulin E
keywords: Basophils; Cellular activation; Histamine; Immune regulation; Monocytes