Aoki, T, Miyakoshi, H, Usuda, Y et al. · Clinical immunology and immunopathology · 1993 · DOI
This study examined whether people with chronic fatigue syndrome (ME/CFS) have lower numbers or reduced function of natural killer (NK) cells, which are part of the immune system that helps fight infections and abnormal cells. The researchers found that some ME/CFS patients showed low NK cell levels or activity, suggesting the immune system may not be working normally in this condition. This finding could help explain why people with ME/CFS experience persistent exhaustion and infections.
This study is significant because it provides early evidence that immune dysfunction—specifically impaired natural killer cells—may be a biological feature of ME/CFS, moving beyond purely psychological explanations. Understanding NK cell abnormalities could eventually lead to biomarkers for diagnosis and guide development of immune-targeted treatments for this debilitating condition.
This study does not prove that low NK cell function causes ME/CFS or that correcting NK dysfunction will cure the condition. The research is descriptive rather than experimental, so it cannot establish whether immune abnormalities are a primary cause, a consequence of illness, or an unrelated finding. It also does not exclude the possibility of other concurrent immune abnormalities contributing to the disease.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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