Immune system and ME/CFS

Whilst no definitive diagnostic test or biomarker has yet been identified for ME/CFS, research shows multiple biological abnormalities, with strong evidence for immune system involvement.

Changes in the immune system may help explain why individuals with ME/CFS experience:

Ongoing “flu-like” symptoms
Increased frequency of infections (e.g. colds) compared to before ME/CFS onset
Flare-ups/worsening of ME/CFS symptoms following infectious episodes

What does the research show?

Key immune findings in ME/CFS research include:

Chronic immune activation and inflammation
- Higher levels of pro-inflammatory molecules (cytokines) and problems in the pathways that detect and coordinate immune responses [1,2,3,4,5]. Evidence of persistent low-grade inflammation, which may contribute to symptoms such as cognitive difficulties and post-exertional malaise [2,6]
- Inflammation in the brain (neuroinflammation), which can be demonstrated with imaging studies [7,8]
Natural killer (NK) cell dysfunction
- NK cells are important defenders in the immune system that identify and kill abnormal or infected cells. Reduced NK cell cytotoxicity (killing/damaging ability) is a consistent finding in ME/CFS research that suggests NK cells may not be as effective in ME/CFS compared to healthy individuals [9]
T and B cell abnormalities
- Altered numbers and activity of T and B cells – immune cells which are central to controlling infections and producing antibodies [1,10,11]
Heightened immune responses to infections
- When exposed to microbes, the innate immune system (the body’s first line of defense) can react too strongly in ME/CFS [12]

Clinical relevance

Whilst no immune-based treatment is yet established, some therapies, e.g. immunoadsorption [13], have been trialled. In practice, immune findings mostly validate the biological nature of ME/CFS, help explain key symptoms, and support the importance of pacing (energy management) and appropriate management of symptoms and comorbidities.