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Open Access Highly Accessed Research article

Age-dependent alterations of monocyte subsets and monocyte-related chemokine pathways in healthy adults

Sebastian Seidler1, Henning W Zimmermann1, Matthias Bartneck2, Christian Trautwein1 and Frank Tacke1*

Author Affiliations

1 Department of Medicine III, University Hospital, RWTH-Aachen, Pauwelsstr 30, 52074 Aachen, Germany

2 Interdisciplinary Centre for Clinical Research, University Hospital, RWTH-Aachen, Pauwelsstr 30, 52074 Aachen, Germany

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BMC Immunology 2010, 11:30  doi:10.1186/1471-2172-11-30

Published: 21 June 2010

Abstract

Background

Recent experimental approaches have unraveled essential migratory and functional differences of monocyte subpopulations in mice. In order to possibly translate these findings into human physiology and pathophysiology, human monocyte subsets need to be carefully revisited in health and disease. In analogy to murine studies, we hypothesized that human monocyte subsets dynamically change during ageing, potentially influencing their functionality and contributing to immunosenescence.

Results

Circulating monocyte subsets, surface marker and chemokine receptor expression were analyzed in 181 healthy volunteers (median age 42, range 18-88). Unlike the unaffected total leukocyte or total monocyte counts, non-classical CD14+CD16+ monocytes significantly increased with age, but displayed reduced HLA-DR and CX3CR1 surface expression in the elderly. Classical CD14++CD16- monocyte counts did not vary dependent on age. Serum MCP-1 (CCL2), but not MIP1α (CCL3), MIP1β (CCL4) or fractalkine (CX3CL1) concentrations increased with age. Monocyte-derived macrophages from old or young individuals did not differ with respect to cytokine release in vitro at steady state or upon LPS stimulation.

Conclusions

Our study demonstrates dynamic changes of circulating monocytes during ageing in humans. The expansion of the non-classical CD14+CD16+ subtype, alterations of surface protein and chemokine receptor expression as well as circulating monocyte-related chemokines possibly contribute to the preserved functionality of the monocyte pool throughout adulthood.