# M1/M2 macrophage polarization

The M1/M2 framework describes two opposite 'modes' your macrophages can switch into. (Macrophages are immune cleanup cells.) M1 macrophages, called classically activated, are turned on by IFN-γ and LPS. They pump out pro-inflammatory signals like TNF-α, IL-6, IL-12, and reactive oxygen species. M2 macrophages, called alternatively activated, are turned on mainly by IL-4 and IL-13 (and calmed by IL-10). They promote tissue repair, debris cleanup, and the resolution of inflammation. Keep in mind that this two-box model is a teaching simplification. Modern gene- and protein-level data show a whole continuum of macrophage states. They do not fit neatly into two poles. With age, tissue macrophages drift toward a dysregulated, inflamed baseline. That weakens the cleanup of acute inflammation. And it feeds the chronic, sterile inflammation behind 'inflammaging'.

## Sources

- Mosser DM, Edwards JP. (2008). Exploring the full spectrum of macrophage activation. Nature Reviews Immunology. https://doi.org/10.1038/nri2448
- Mahbub S, Deburghgraeve CR, Kovacs EJ. (2012). Advanced Age Impairs Macrophage Polarization. Journal of Interferon & Cytokine Research. https://doi.org/10.1089/jir.2011.0058

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_Canonical: https://longevity-switzerland.com/en/glossary/macrophage-polarization · Part of Longevity Cities · Updated 2026-06-22_