Human macrophages induced in vitro by macrophage colony-stimulating factor are deficient in IL-12 production.
IL-12 is important for Th1 differentiation. Myeloid-derived antigen-presenting cells (APC) such as monocytes, macrophages (Mphi) and dendritic cells (DC) are believed to be major sources of IL-12 in vivo. We have compared IL-12 production of fresh monocytes with Mphi differentiated in vitro using macrophage colony-stimulating factor (M-CSF) or human plasma, and in vitro generated dendritic cells, since these differentiated cell types represent APC at sites of antigen challenge. Macrophages stimulated with lipopolysaccharide (LPS) or heat-killed Listeria monocytogenes in the presence or absence of IFN-gamma produced minimal IL-12 p70 by comparison with DC or monocytes, despite comparable production of TNF-alpha. M-CSF-induced Mphi produced low levels of IL-10 constitutively and high levels after stimulation with LPS, but neutralization of IL-10 did not augment Mphi IL-12 production. Exposure of Mphi to TNF-alpha, granulocyte-macrophage CSF or IFN-gamma did not substantially up-regulate IL-12. Therefore M-CSF induces a differentiated Mphi phenotype in which IL-12 production is down-regulated, perhaps irreversibly. This may be the default pathway for monocyte-Mphi development in the absence of inflammation.
The TVW Telethon Institute for Child Health Research, Subiaco, Western Australia, Australia. williams@ichr.uwa.edu.au
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D002454:Cell Differentiation / Q000187:drug effects; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D016753:Interleukin-10 / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis* / Q000172:deficiency; D008089:Listeria monocytogenes / Q000276:immunology; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000276:immunology*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D009500:Neutralization Tests; D010641:Phenotype
D016753:Interleukin-10; D018664:Interleukin-12; D016173:Macrophage Colony-Stimulating Factor