Patarca, R · Annals of the New York Academy of Sciences · 2001 · DOI
Quick Summary
This study found that people with ME/CFS show signs of immune system activation (more active immune cells and elevated immune signaling molecules), yet paradoxically have weak immune function (poor natural killer cell activity and weak responses to infections). The immune system appears to be stuck in an imbalanced state, favoring certain types of inflammatory responses, which may relate to symptom cycles of improvement and worsening.
Why It Matters
Understanding the immune dysfunction pattern in ME/CFS—the paradox of apparent activation with actual functional impairment—is critical for developing targeted therapies. This work helped frame immune dysregulation as a central disease mechanism rather than a secondary feature, opening avenues for immunological interventions.
Observed Findings
Increased numbers of activated T lymphocytes and cytotoxic T cells in CFS patients
Elevated circulating cytokine levels
Low natural killer cell cytotoxicity (NKCC)
Poor lymphocyte proliferation in response to mitogens
Selective immunoglobulin deficiencies, particularly IgG1 and IgG3
Inferred Conclusions
ME/CFS involves a paradoxical immune state: simultaneous activation and functional impairment
Th2/proinflammatory cytokine predominance may perpetuate disease through remission/exacerbation cycles
Immune dysregulation may be triggered or worsened by latent pathogen reactivation
Cytokine-targeted therapeutic interventions may offer therapeutic promise
Remaining Questions
What causes the initial shift toward Th2 predominance and functional immune impairment in ME/CFS?
Do cytokine abnormalities drive symptom severity and relapse cycles, or are they secondary consequences?
What This Study Does Not Prove
This review does not establish whether immune abnormalities are a primary cause of ME/CFS, a consequence of the illness, or both. It also does not prove that manipulating cytokine patterns will improve patient outcomes, only that such intervention appears theoretically promising. The temporal relationship between immune changes and symptom cycles remains uncertain.
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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