COVID-19 Causes A New Medical Condition to Emerge: Long COVID Monocyte State (LC Mo)
Nikhil Prasad Fact checked by:Thailand Medical News Team Jan 18, 2026 1 hour, 51 minutes ago
Medical News: Long COVID continues to puzzle doctors and patients alike, with many sufferers experiencing crushing fatigue, breathing difficulties, and poor quality of life long after the initial infection has passed. A new large scale scientific investigation has now identified a specific immune cell state that appears to sit at the heart of these prolonged symptoms, offering fresh insight into why recovery stalls for some people.
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A detailed study reveals how abnormal monocytes may drive long lasting fatigue and lung problems in
long COVID patients
A Broad International Research Effort
The study was conducted by researchers from several leading institutions, including Hannover Medical School and the Helmholtz Centre for Infection Research in Germany, the University of Duisburg Essen, Mayo Clinic in the United States, Radboud University Medical Center in the Netherlands, and collaborating academic centers across Europe and Asia. The team examined blood and lung samples from multiple patient groups, including people with long COVID, those who fully recovered, and individuals never infected.
Discovery Of a Distinct Immune Pattern
Using advanced single cell and molecular analysis, the researchers identified a unique immune signature in long COVID patients. This signature was found mainly in monocytes, a type of white blood cell that normally helps fight infections and repair damaged tissue. The altered monocyte state was named LC Mo, short for long COVID monocyte state.
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Medical News report explains that LC Mo was especially common in people who initially had mild or moderate COVID but later developed long lasting symptoms, suggesting that severe early illness is not required for long term immune disruption.
What Exactly Is LC Mo
LC Mo represents a state where monocytes are no longer behaving normally. Instead of switching off after an infection clears, these cells remain stuck in a confusing mixed mode. They show signs of ongoing inflammation while simultaneously activating pathways linked to tissue remodeling and scarring. This includes strong activity in TGF-beta and WNT-beta catenin signaling pathways, which are usually involved in wound healing but can cause harm if overactivated for long periods.
At the same time, LC Mo cells display abnormal regulation of key immune control systems driven by transcription factors such as NF-kappa-B and AP-1. These changes push the cells toward a pro fibrotic and inflammatory profile. In simple terms, LC Mo monocytes act like immune cells that think damage is still ongoing, even months after the virus has gone.
Links To Fatigue and Lung Damage
The presence of LC Mo cells strongly matched symptom severity. Patients with higher levels of these cells reported more extreme fatigue and worse breathlessness. Blood tests showed persistently raised inflammatory proteins such as TNF, CCL2, and CXCL11, all of which can interfere with energy levels and oxygen delivery.
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Crucially, similar LC Mo like cells were found in lung samples from patients with serious breathing problems. These lung immune cells expressed genes linked to fibrosis, or scarring, providing a biological explanation for reduced lung function seen in many long COVID sufferers.
A Weakened Immune Response
Another worrying finding was that people with high LC Mo activity showed impaired interferon responses. Interferons are vital for controlling viral threats. Even long after recovery, these immune systems responded poorly to stimulation, suggesting lasting immune dysfunction rather than hidden infection.
Conclusion
This research provides strong evidence that long COVID is driven by persistent immune misfiring rather than imagination or anxiety. The LC Mo monocyte state connects chronic inflammation, fatigue, lung scarring, and weak immune defenses into one clear mechanism. Understanding LC Mo may lead to better diagnostic markers and targeted treatments that calm these cells, restore immune balance, and finally allow true recovery for millions worldwide.
The study findings were published in the peer reviewed journal: Nature Immunology.
https://www.nature.com/articles/s41590-025-02387-1
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Read Also:
https://www.thailandmedical.news/articles/coronavirus
https://www.thailandmedical.news/articles/long-covid
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