[Role of pathological delayed-type hypersensitivity in chronic fatigue syndrome: importance of the evaluation of lymphocyte activation by flow cytometry and the measurement of urinary neopterin]. — CFSMEATLAS
[Role of pathological delayed-type hypersensitivity in chronic fatigue syndrome: importance of the evaluation of lymphocyte activation by flow cytometry and the measurement of urinary neopterin].
Brunet, J L, Fatoohi, F, Liaudet, A Perret et al. · Allergie et immunologie · 2002
Quick Summary
This study investigated whether ME/CFS patients have exaggerated immune reactions to common fungi and bacteria that normally live on or around our bodies. Researchers tested this by placing small amounts of Candida (a common yeast) under the skin and watching for delayed reactions. They found that about half of ME/CFS patients showed these heightened reactions, and they developed methods to measure immune cell activation in the lab that matched what they saw on the skin.
Why It Matters
This work identifies a potential biological marker—abnormal immune hypersensitivity—that could help subgroup ME/CFS patients and guide targeted immunological research. The methodological approach combining skin testing, flow cytometry, and neopterin measurement offers a standardized framework for evaluating immune dysregulation in this population.
Observed Findings
Approximately 50% of ME/CFS patients demonstrated pathological delayed-type hypersensitivity responses to Candida albicans antigens
Intensity of skin DTH responses correlated with the degree of T-cell activation measured by flow cytometry in vitro
T-cell activation to Candida could be reliably detected using three-color flow cytometry (CD3, CD4, and CD69/CD25)
Urinary neopterin kinetics during skin testing provided an additional parameter reflecting immune activation
Inferred Conclusions
A subset of ME/CFS patients exhibit pathological hypersensitivity to common environmental antigens, suggesting dysregulated immune responses
Flow cytometry-based lymphocyte activation assays correlate with clinical DTH responses and may serve as objective biomarkers
Multifactorial immune dysfunction rather than a single mechanism likely contributes to ME/CFS pathophysiology
Remaining Questions
Is the observed DTH response a primary driver of fatigue symptoms or an epiphenomenon?
Why do only ~50% of ME/CFS patients show this response—what distinguishes the responsive subset?
Does neopterin elevation precede symptom onset or develop secondarily to chronic illness?
What This Study Does Not Prove
This study does not establish that delayed-type hypersensitivity causes ME/CFS fatigue, only that the two occur together in some patients. It does not prove the finding applies to all ME/CFS patients, since only ~50% showed this response. The cross-sectional design prevents determination of whether immune dysregulation precedes symptom onset or develops as a consequence of illness.