CX3CL1/fractalkine is released from apoptotic lymphocytes to stimulate macrophage chemotaxis

LA Truman, CA Ford, M Pasikowska… - Blood, The Journal …, 2008 - ashpublications.org
LA Truman, CA Ford, M Pasikowska, JD Pound, SJ Wilkinson, IE Dumitriu, L Melville…
Blood, The Journal of the American Society of Hematology, 2008ashpublications.org
Cells undergoing apoptosis are efficiently located and engulfed by phagocytes. The
mechanisms by which macrophages, the professional scavenging phagocytes of apoptotic
cells, are attracted to sites of apoptosis are poorly defined. Here we show that
CX3CL1/fractalkine, a chemokine and intercellular adhesion molecule, is released rapidly
from apoptotic lymphocytes, via caspase-and Bcl-2-regulated mechanisms, to attract
macrophages. Effective chemotaxis of macrophages to apoptotic lymphocytes is dependent …
Abstract
Cells undergoing apoptosis are efficiently located and engulfed by phagocytes. The mechanisms by which macrophages, the professional scavenging phagocytes of apoptotic cells, are attracted to sites of apoptosis are poorly defined. Here we show that CX3CL1/fractalkine, a chemokine and intercellular adhesion molecule, is released rapidly from apoptotic lymphocytes, via caspase- and Bcl-2-regulated mechanisms, to attract macrophages. Effective chemotaxis of macrophages to apoptotic lymphocytes is dependent on macrophage fractalkine receptor, CX3CR1. CX3CR1 deficiency caused diminished recruitment of macrophages to germinal centers of lymphoid follicles, sites of high-rate B-cell apoptosis. These results provide the first demonstration of chemokine/chemokine-receptor activity in the navigation of macrophages toward apoptotic cells and identify a mechanism by which macrophage infiltration of tissues containing apoptotic lymphocytes is achieved.
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