The Good and the Bad: Monocytes' and Macrophages' Diverse Functions in Inflammation

Cells. 2022 Jun 20;11(12):1979. doi: 10.3390/cells11121979.


Monocytes and macrophages are central players of the innate immune response and play a pivotal role in the regulation of inflammation. Thereby, they actively participate in all phases of the immune response, from initiating inflammation and triggering the adaptive immune response, through to the clearance of cell debris and resolution of inflammation. In this review, we described the mechanisms of monocyte and macrophage adaptation to rapidly changing microenvironmental conditions and discussed different forms of macrophage polarization depending on the environmental cues or pathophysiological condition. Therefore, special focus was placed on the tight regulation of the pro- and anti-inflammatory immune response, and the diverse functions of S100A8/S100A9 proteins and the scavenger receptor CD163 were highlighted, respectively. We paid special attention to the function of pro- and anti-inflammatory macrophages under pathological conditions.

Keywords: CD163; COVID-19; S100A8; S100A9; SIRS; chronic inflammation; inflammation; macrophage plasticity; macrophages; monocytes.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Inflammatory Agents / metabolism
  • Calgranulin A / metabolism
  • Humans
  • Inflammation / pathology
  • Macrophages* / metabolism
  • Monocytes* / metabolism


  • Anti-Inflammatory Agents
  • Calgranulin A

Grants and funding

This research was funded by grants from the Interdisciplinary Center of Clinical Research at the University of Muenster (Ro2/007/22), the German Research Foundation (DFG) CRC 1009 (projects B09, Z01, Z02 to J.R.), CRU 342 (project P3 to K.B-K. and J.R.); CRC1450 (project C01 to J.R.) and EU IMI (project MI2-2018-14-02 to J.R.). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.