For most people, when their infection clears, COVID-19 symptoms cease and production of this protein stops, but the researchers found that high levels of persisted in some Long COVID patients for up to 31 months.
News Medical
Summary
- A University of Cambridge study identifies interferon gamma (IFN-γ) as a potential biomarker for Long COVID fatigue, with high levels persisting in some patients for up to 31 months.
- The study links the continued production of IFN-γ to specific immune cells (CD8+ T cells) interacting with CD14+ monocytes.
- Dr Charles Shepherd commented that similar raised levels of inflammatory cytokines have also been seen in ME/CFS. While existing clinical trials using medications to treat this have not produced any significant results, this is still an area worthy of more research.
Extracts
A University of Cambridge-led study identifies the protein interferon gamma (IFN-γ) as a potential biomarker for Long COVID fatigue and highlights an immunological mechanism underlying the disease, which could pave the way for the development of much needed therapies, and provide a head start in the event of a future coronavirus pandemic.
The study, published today in Science Advances, followed a group of patients with Long COVID fatigue for over 2.5 years, to understand why some recovered and others did not.
The study shows that initial infection with SARS-CoV-2 triggers production of the antiviral protein IFN-γ, which is a normal reaction from the immune system. For most people, when their infection clears, COVID-19 symptoms cease and production of this protein stops, but the researchers found that high levels of IFN-γ persisted in some Long COVID patients for up to 31 months.
By conducting ‘cell depletion assays', the team managed to identify the precise cell types responsible for producing IFN-γ. They pinpointed immune cells known as CD8+ T cells but found that they required contact with another immune cell type: CD14+ monocytes.
Previous studies have identified IFN-γ signatures using different approaches and cohorts, but this study's focus on fatigue revealed a much stronger influence. Also, while previous studies have noticed IFN-y levels rising, they have not followed patients long enough to observe when they might drop back down.
MEA Comment
New research from the University of Cambridge indicates that continued production of an immune system chemical (cytokine) called interferon gamma may be related to symptoms such as fatigue, muscle pain and headaches in Long Covid.
Not surprising, research into ME/CFS has also found raised levels of inflammatory cytokines in ME/CFS, including interferon gamma, and linked this to the on-going infective type symptoms.
There are existing drug treatments that can help to dampen down this type of immune system inflammation. However, results from small clinical trials in ME/CFS have not produced any really significant results.
Even so this is an area of drug treatment intervention in both Long Covid and ME/CFS that is worthy of further research.
Dr Charles Shepherd,
Trustee and Hon. Medical Adviser to the ME Association,
Member of the 2018-2021 NICE guideline on ME/CFS committee,
Member of the 2002 Chief Medical Officer's Working Group on ME/CFS
More Information
- Identifying antiviral protein as a potential biomarker for Long Covid | February 26, 2024