Serologic and immunologic responses in chronic fatigue syndrome with emphasis on the Epstein-Barr virus

Although patients with chronic fatigue syndrome (CFS) can be diagnosed by clinical criteria, the lack of specific laboratory criteria delays or prevents the diagnosis and contributes to the quasi-disease status of the syndrome. A resurgence of interest in the syndrome has followed reports suggesting that CFS may be associated with chronic active infection due to the Epstein-Barr virus. Analysis of reports to date shows that the mean titers of antibodies to viral capsid antigen and to early antigen are greater for patients with CFS than for healthy individuals; this is particularly evident in cases for which serial samples were tested. However, these differences do not prove the cause of CFS. Cell-mediated immune responses in patients with CFS vary from study to study, and the number and function of natural killer cells in those patients are the most variable factors. Rates of isolation of virus from saliva do not differ, but in one comparison study with a large number of subjects, more lymphocytes that contained virus were isolated from patients than from controls. Other viruses, such as the Coxsackie B virus, have been implicated as causes of CFS in studies from Great Britain. The use of a working definition of CFS and standardized tests to address abnormalities revealed by laboratory tests among homogeneous populations should allow determination of useful tests for the diagnosis of CFS and studies of its mechanisms.