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Platelet Factor 4/CXCL4 Induces Phagocytosis and the Generation of Reactive Oxygen Metabolites in Mononuclear Phagocytes Independently of Gi Protein Activation or Intracellular Calcium Transients

Olga Pervushina, Barbara Scheuerer, Norbert Reiling, Lars Behnke, Jens-M Schröder, Brigitte Kasper, Ernst Brandt, Silvia Bulfone-Paus, Frank Petersen

J Immunol. 2004 Aug 1;173(3):2060-7.

PMID: 15265941

Abstract:

Platelet factor 4 (PF-4), a platelet-derived CXC chemokine, is known to prevent human monocytes from apoptosis and to promote differentiation of these cells into HLA-DR(-) macrophages. In this study, we investigated the role of PF-4 in the control of acute monocyte proinflammatory responses involved in the direct combat of microbial invaders. We show that PF-4 increases monocyte phagocytosis and provokes a strong formation of oxygen radicals but lacks a chemotactic activity in these cells. Compared with FMLP, PF-4-induced oxidative burst was later in its onset but was remarkably longer in its duration (lasting for up to 60 min). Furthermore, in PF-4-prestimulated cells, FMLP- as well as RANTES-induced burst responses became synergistically enhanced. As we could show, PF-4-mediated oxidative burst in monocytes does not involve Gi proteins, elevation of intracellular free calcium concentrations, or binding to CXCR3B, a novel PF-4 receptor recently discovered on endothelial cells. Moreover, we found that PF-4 acts on macrophages in a dual manner. On the one hand, very similar to GM-CSF or M-CSF, PF-4 treatment of monocytes generates macrophages with a high capacity for unspecific phagocytosis. On the other hand, short term priming of GM-CSF-induced human macrophages with PF-4 substantially increases their capability for particle ingestion and oxidative burst. A comparable effect was also observed in murine bone marrow-derived macrophages, indicating cross-reactivity of human PF-4 between both species. Taken together, PF-4 may play a crucial role in the induction and maintenance of an unspecific immune response.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
IAR42413100 PF-4 (CXCL4) human PF-4 (CXCL4) human Price
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