Monocytes %

Monocytes are a type of white blood cell that act as your body’s clean-up and repair crew. They circulate in the bloodstream, searching for signs of infection, inflammation, or tissue damage. Once they reach the site of injury, they transform into two powerful immune cells:

• Macrophages, which “eat” bacteria, viruses, and dead cells to keep tissues clean.

• Dendritic cells, which act as communicators — they present fragments of pathogens to T cells, helping your immune system remember and respond faster next time.

Monocytes bridge the gap between immediate defense and long-term immunity. When infection strikes, neutrophils are first on the scene — the fast responders. They neutralize invaders and release chemical signals that summon monocytes. These monocytes then move into the tissue, where they finish the job by clearing debris and promoting repair.

However, when inflammation becomes excessive or uncontrolled (like during a cytokine storm), monocytes can contribute to tissue damage instead of healing — highlighting why immune balance is so important.

If the monocyte percentage is higher than normal, it may mean the body is fighting an infection, dealing with inflammation, or responding to stress. High monocyte levels can be seen in chronic diseases like heart disease, rheumatoid arthritis, and some types of cancer. Monocytes play a key role in atherosclerosis (hardening of the arteries) by helping form plaques in blood vessels. Changes in monocyte levels can also be linked to autoimmune diseases, lung problems, and metabolic conditions.

Low monocyte levels are less common and may be seen with certain infections or after taking some medications. Monocyte function and numbers can be affected by age, sex, ethnicity, sleep, diet, and exercise. The gut microbiome (the community of bacteria in the digestive tract) can also influence monocyte activity and may affect inflammation and disease risk.

• Infections: Bacterial, viral, or chronic infections increase monocyte levels.

• Inflammation: Autoimmune or inflammatory diseases can raise monocyte counts.

• Stress and recovery: Physical or emotional stress can temporarily affect levels.

• Bone marrow health: Suppression or overactivation can alter production.

• Support immune balance: Eat a whole-food, anti-inflammatory diet rich in antioxidants, omega-3s, and fibre.

• Manage stress and sleep: Chronic stress can drive inflammation and alter white blood cell balance.

• Avoid chronic inflammatory triggers: Reduce processed foods, excessive alcohol, and exposure to environmental toxins.

• Stay active: Moderate, consistent movement improves immune cell turnover and function.

1. Narasimhan, P. B., Marcovecchio, P., Hamers, A. A. J., & Hedrick, C. C. (2019). Nonclassical monocytes in health and disease. Annual Review of Immunology, 37, 439–456. https://doi.org/10.1146/annurev-immunol-042617-053119

2. Ghattas, A., Griffiths, H. R., Devitt, A., Lip, G. Y., & Shantsila, E. (2013). Monocytes in coronary artery disease and atherosclerosis: Where are we now? Journal of the American College of Cardiology, 62(17), 1541–1551. https://doi.org/10.1016/j.jacc.2013.07.043

3. Ożańska, A., Szymczak, D., & Rybka, J. (2020). Pattern of human monocyte subpopulations in health and disease. Scandinavian Journal of Immunology, 92(1), e12883. https://doi.org/10.1111/sji.12883

4. Patel, A. A., & Yona, S. (2019). Inherited and environmental factors influence human monocyte heterogeneity. Frontiers in Immunology, 10, 2581. https://doi.org/10.3389/fimmu.2019.02581

5. Cormican, S., & Griffin, M. D. (2020). Human monocyte subset distinctions and function: Insights from gene expression analysis. Frontiers in Immunology, 11, 1070. https://doi.org/10.3389/fimmu.2020.01070

6. Ruder, A. V., Wetzels, S. M. W., Temmerman, L., Biessen, E. A. L., & Goossens, P. (2023). Monocyte heterogeneity in cardiovascular disease. Cardiovascular Research, 119(11), 2033–2045. https://doi.org/10.1093/cvr/cvad069

7. Cignarella, A., Tedesco, S., Cappellari, R., & Fadini, G. P. (2018). The continuum of monocyte phenotypes: Experimental evidence and prognostic utility in assessing cardiovascular risk. Journal of Leukocyte Biology. https://doi.org/10.1002/JLB.5RU1217-477RR

8. Wolf, A. A., Yáñez, A., Barman, P. K., & Goodridge, H. S. (2019). The ontogeny of monocyte subsets. Frontiers in Immunology, 10, 1642. https://doi.org/10.3389/fimmu.2019.01642

9. Robinson, A., Han, C. Z., Glass, C. K., & Pollard, J. W. (2021). Monocyte regulation in homeostasis and malignancy. Trends in Immunology, 42(2), 104–119. https://doi.org/10.1016/j.it.2020.12.001

10. Vlacil, A. K., Schuett, J., Schieffer, B., & Grote, K. (2019). Variety matters: Diverse functions of monocyte subtypes in vascular inflammation and atherogenesis. Vascular Pharmacology, 113, 9–19. https://doi.org/10.1016/j.vph.2018.12.002

11. Bashore, A. C., Xue, C., Kim, E., et al. (2024). Monocyte single-cell multimodal profiling in cardiovascular disease risk states. Circulation Research, 135(6), 685–700. https://doi.org/10.1161/CIRCRESAHA.124.324457

12. Kolypetri, P., & Weiner, H. L. (2023). Monocyte regulation by gut microbial signals. Trends in Microbiology, 31(10), 1044–1057. https://doi.org/10.1016/j.tim.2023.05.006