[Chronic fatigue syndrome--study of 51 cases treated at the Second Tokyo National Hospital].

Fifty-one patients with chronic fatigue syndrome (CFS) were studied. Tender points, which are a characteristic clinical feature of fibromyalgia, were found in all but two of the patients at 11.4 points (mean) per patient. IgG antibody titers to EB virus viral capsid antigen were more elevated in the CFS patient group compared to that of the control (p < 0.0015). IgG antibody titers to HHV-6 were not higher in the patient group. NK cell activity was not more decreased in the patient group, whereas, the mean number of NK cells was lower (p < 0.005) in the patient group, when CD57 was used as the NK cell marker. Viral infections and/or disorders in cellular immunity may be important factors in the pathogenesis of CFS.