Letter to the editor re: 'A formal analysis of cytokine networks in chronic fatigue syndrome' by Broderick et al.

摘要

I read with great interest the paper by Broderick G. et al. "A formal analysis of cytokine networks in Chronic Fatigue Syndrome" published in your journal, Brain Behavior and Immunity (2010). I certainly agree with the conclusions reached by the authors as to the importance of the cytokines IL-2, IFN-y and TNF-a in this syndrome and the indication of a probable viral infection in its aetio-pathogenesis. However my perplexity lies in the method used, which as I understand was the measurement via ELISA of cytokine serum concentrations in morning blood samples, comparing them with healthy controls. In fact there are numerous reports of a cir-cadian rhythm to cytokine secretion, and for TNF-a in particular an overlap in concentrations in healthy control subjects according to whether they had slept properly or been wakeful. Patients with Chronic Fatigue Syndrome, in my experience have often complained of either insomnia or of hypersomnia - this would make a single evaluation of cytokine concentrations misleading with respect to healthy control subjects.