A study estimated about 1.8 trillion immune cells with a combined mass of 1.2 kg in a model of a 73 kg adult man. Of the 11 cell types compared, neutrophils were most numerous at about 700 billion, and macrophages contributed the most mass at about 600 grams (Sender et al., 2023).
Individual macrophages are relatively large, which helps explain their share of the combined mass. The linked rankings use rounded estimates from Table 1 and show the study’s 95% confidence intervals (Sender et al., 2023).
References
Sender, R., Weiss, Y., Navon, Y., Milo, I., Azulay, N., Keren, L., Fuchs, S., Ben-Zvi, D., Noor, E., & Milo, R. (2023). The total mass, number, and distribution of immune cells in the human body. Proceedings of the National Academy of Sciences, 120(44), Article e2308511120. https://doi.org/10.1073/pnas.2308511120
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Macrophage by NIAID by National Institute of Allergy and Infectious Diseases. CC BY 2.0. Resized, lightly color-graded and composited onto a plum gradient.
