Biphenotypic B/macrophage cells express COX-1 and up-regulate COX-2 expression and prostaglandin E(2) production in response to pro-inflammatory signals.

Graf BA, Nazarenko DA, Borrello MA, Roberts LJ, Morrow JD, Palis J, Phipps RP
Eur J Immunol. 1999 29 (11): 3793-803

PMID: 10556836 · DOI:10.1002/(SICI)1521-4141(199911)29:11<3793::AID-IMMU3793>3.0.CO;2-3

B/macrophage cells are biphenotypic leukocytes of unknown function that simultaneously express B lymphocyte (IgM, IgD, B220, CD5) and macrophage (phagocytosis, F4/80, Mac-1) characteristics. B/macrophage cells can be generated from purified mouse B lymphocytes incubated in fibroblast-conditioned medium. A potential role for B/macrophage cells in inflammation was shown by their ability to express prostaglandin H synthase-1 (COX-1) and prostaglandin H synthase-2 (COX-2) and by their production of prostaglandin (PG) E(2). COX-1 and COX-2 mRNA expression is not observed in the precursor B lymphocytes and is not known to be a property of B lineage cells. In contrast, COX-2 and the prostanoids PGE(2), PGF(2alpha) and PGD(2) are highly inducible in B/ macrophage cells upon stimulation with lipopolysaccharide, CD40 ligand, or via engagement of surface IgM, supporting a role for these cells in inflammation. PGD(2) and its metabolites are of interest because they activate the nuclear receptor PPARgamma that regulates lipid metabolism. The B/macrophage represents the first instance of a normal B-lineage cell capable of expressing COX-2. Importantly, B/macrophage cells were identified in vivo, providing evidence that they may play a significant role in immune responses. Since PGE(2) blunts IL-12 production, its synthesis by B/macrophage cells may shift the balance of an immune response towards Th2 and humoral immunity.

MeSH Terms (21)

Animals B-Lymphocytes Blotting, Western Cells, Cultured Cyclooxygenase 1 Cyclooxygenase 2 Dinoprost Dinoprostone Gene Expression Regulation, Enzymologic Immunohistochemistry Immunophenotyping Isoenzymes Macrophages Membrane Proteins Mice Prostaglandin-Endoperoxide Synthases Prostaglandin D2 Reverse Transcriptase Polymerase Chain Reaction RNA, Messenger Signal Transduction Up-Regulation

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