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Volume 11 (2011), Pages 2391-2402
Review Article

Macrophage Polarization in Health and Disease

1Department of Developmental and Molecular Biology, Center for the Study of Reproductive Biology and Women's Health, Albert Einstein College of Medicine, Bronx, NY 10461, USA
2Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
3AIDS Immunopathogenesis Unit, Division of Immunology, Transplantation and Infectious Diseases, School of Medicine, San Raffaele Scientific Institute and Vita-Salute San Raffaele University, P2/P3 Laboratories, DIBIT-1, Via Olgettina No. 58, 20132 Milano, Italy

Received 30 October 2011; Accepted 9 November 2011

Academic Editor: Marco Antonio Cassatella

Copyright © 2011 Luca Cassetta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Macrophages are terminally differentiated cells of the mononuclear phagocyte system that also encompasses dendritic cells, circulating blood monocytes, and committed myeloid progenitor cells in the bone marrow. Both macrophages and their monocytic precursors can change their functional state in response to microenvironmental cues exhibiting a marked heterogeneity. However, there are still uncertainties regarding distinct expression patterns of surface markers that clearly define macrophage subsets, particularly in the case of human macrophages. In addition to their tissue distribution, macrophages can be functionally polarized into M1 (proinflammatory) and M2 (alternatively activated) as well as regulatory cells in response to both exogenous infections and solid tumors as well as by systems biology approaches.