Oxidative stress index and mononuclear cell surface antigen analysis in patients with chronic fatigue syndrome

Abstract

Chronic fatigue syndrome (CFS) is characterized by severe fatigue and various nonspecific symptoms such as fever, headache, muscle pain, and sleep disorder. CFS is a highly heterogeneous and partly subjective illness, and no standard laboratory test is currently available for its reliable diagnosis. The main objective of this study was to establish biomarkers useful for the diagnosis of CFS. We analyzed the oxidative stress index (OSI) and peripheral mononuclear cell surface antigens in healthy subjects and CFS patients whose diagnosis was based on clinical signs. The OSI was significantly higher in sera of the CFS patients than in those of the healthy subjects. Our results indicate the possibility that OSI is a useful biomarker for the objective diagnosis of CFS. On the other hand, we confirmed by lymphocyte subset analysis that the proportion of B cells was significantly higher in the CFS patients than in the healthy subjects. Furthermore, the surface antigen analysis of monocytes revealed that the proportion of CD14⁺/CD16⁻ monocytes was significantly lower and that of CD14⁺/CD16⁺ monocytes was significantly higher in the CFS patients than in the healthy subjects. It is quite interesting to find this higher proportion of CD14⁺/CD16⁺ monocytes, which are associated with inflammatory diseases and autoimmune diseases, in the CFS patients whose diagnosis was based on clinical signs. In addition, there was a significant correlation between the OSI and the proportion of inflammatory monocytes in the CFS patients. These findings suggest that chronic inflammation caused by oxidative stress might be involved in the pathogenesis of CFS.