Macrophage

Definition

A macrophage is an innate immune cell that helps detect, engulf, and digest microbes, dead cells, cellular debris, and other material in tissues. Macrophages also release signalling molecules, present antigens to other immune cells, and help coordinate inflammation, tissue repair, and resolution after injury or infection. [1] [2] [3]

Why It Matters in Ageing Research

Macrophages matter in ageing research because they sit at the intersection of immunity, inflammation, tissue maintenance, and repair. Age-related changes in macrophage function can influence chronic inflammation, impaired wound healing, altered clearance of senescent cells, metabolic dysfunction, and tissue-specific ageing processes. [4] [5] [6]

Common Confusion

• Macrophages are not only “garbage collectors”; they also regulate inflammation, repair, metabolism, and immune signalling.
• Macrophages are part of innate immunity, but they can shape adaptive immune responses by presenting antigens and releasing cytokines.
• Macrophage behaviour is context-dependent; simple labels such as “pro-inflammatory” or “repair-oriented” can miss important tissue-specific differences.

Related Reading

• Immunosenescence
• Inflammaging
• Macrophage Polarization
• Cellular Senescence
• SASP

References

1. Gordon, S., & Taylor, P. R. (2005). Monocyte and macrophage heterogeneity. https://doi.org/10.1038/nri1733
2. Wynn, T. A., Chawla, A., & Pollard, J. W. (2013). Macrophage biology in development, homeostasis and disease. https://doi.org/10.1038/nature12034
3. Murray, P. J., & Wynn, T. A. (2011). Protective and pathogenic functions of macrophage subsets. https://doi.org/10.1038/nri3073
4. Franceschi, C., & Campisi, J. (2014). Chronic inflammation (inflammaging) and its potential contribution to age-associated diseases. https://doi.org/10.1093/gerona/glu057
5. Fulop, T., Larbi, A., Dupuis, G., et al. (2017). Immunosenescence and Inflamm-Aging As Two Sides of the Same Coin: Friends or Foes? https://doi.org/10.3389/fimmu.2017.01960
6. Nikolich-Zugich, J. (2018). The twilight of immunity: emerging concepts in aging of the immune system. https://doi.org/10.1038/s41590-017-0006-x