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Interleukin‐4 can induce interleukin‐4 production in dendritic cells
Author(s) -
Maroof Asher,
Penny Michelle,
Kingston Rosetta,
Murray Clare,
Islam Sabita,
Bedford Penelope A.,
Knight Stella C.
Publication year - 2006
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1111/j.1365-2567.2005.02305.x
Subject(s) - autocrine signalling , cytokine , stat protein , paracrine signalling , microbiology and biotechnology , biology , interleukin , interleukin 3 , receptor , signal transduction , immunology , il 2 receptor , t cell , stat3 , immune system , biochemistry
Summary The presence of interleukin‐4 (IL‐4) during the generation of dendritic cells (DC) from precursor cells results in measurable increases of IL‐12 in supernatants but IL‐4 secretion has not been reported. However, DC have IL‐4 receptors and are able to make IL‐4. We therefore sought evidence for autocrine effects of IL‐4 on DC. IL‐4 gene expression was low in DC generated from bone‐marrow stem cells in the presence of granulocyte–macrophage colony‐stimulating factor but was up‐regulated by exposure of the developing DC to IL‐4. Exposure to IL‐4 also induced intracellular IL‐4 production in DC. The intracellular IL‐4 induced in the presence of IL‐4 was increased following further DC maturation with tumour necrosis factor‐α. By contrast, in supernatants of DC, IL‐4 was rarely detected and only at late culture periods. However, after exposure of DC to IL‐4, cell‐bound IL‐4 was detected transiently, which suggested binding and internalization of the cytokine. Binding via IL‐4 receptor‐α was indicated from phosphorylation of the signal transducer and activator of transcription (STAT) protein 6, which is known to mediate IL‐4 function. Cytokine persisting within the supernatants of the cells may therefore be unrepresentative of the actual production and function of IL‐4 in the cells; IL‐4 may be produced in DC in response to exposure to IL‐4 but may then be lost from the supernatants during cell binding and activation of the cells.