Monocyte-Mediated Defense Against Microbial Pathogens

Annu Rev Immunol. 2007 Dec 3 [Epub ahead of print]

Monocyte-Mediated Defense Against Microbial Pathogens

Serbina NV, Jia T, Hohl TM, Pamer EG.

Infectious Diseases Unit, Department of Medicine, Sloan Kettering Cancer Institute, New York, New York 10021; email: serbinan@mskcc.org.

Circulating blood monocytes supply peripheral tissues with macrophage and dendritic cell (DC) precursors and, in the setting of infection, also contribute directly to immune defense against microbial pathogens. In humans and mice, monocytes are divided into two major subsets that either specifically traffic into inflamed tissues or, in the absence of overt inflammation, constitutively maintain tissue macrophage/DC populations. Inflammatory monocytes respond rapidly to microbial stimuli by secreting cytokines and antimicrobial factors, express the CCR2 chemokine receptor, and traffic to sites of microbial infection in response to monocyte chemoattractant protein (MCP)-1 (CCL2) secretion. In murine models, CCR2- mediated monocyte recruitment is essential for defense against Listeria monocytogenes, Mycobacterium tuberculosis, Toxoplasma gondii, and Cryptococcus neoformans infection, implicating inflammatory monocytes in defense against bacterial, protozoal, and fungal pathogens. Recent studies indicate that inflammatory monocyte recruitment to sites of infection is complex, involving CCR2-mediated emigration of monocytes from the bone marrow into the bloodstream, followed by trafficking into infected tissues. The in vivo mechanisms that promote chemokine secretion, monocyte differentiation and trafficking, and finally monocyte-mediated microbial killing remain active and important areas of investigation. Expected final online publication date for the Annual Review of Immunology Volume 26 is March 19, 2008. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.

PMID: 18303997 [PubMed - as supplied by publisher]