beta-endorphin concentrations are decreased in peripheral blood mononuclear cells of chronic fatigue syndrome patients: Comparison with depression

Chronic Fatigue Syndrome [CFS] has uncertain etiology, and diagnosis overla ps with depression. Since most studies suggest an activation of immune resp onses in CFS, and the opioid peptide beta-endorphin [BE] content in periphe ral blood mononuclear cells BE was shown to be decreased when the immune sy stem is activated, and increased when it is depressed, it seemed worthwhile to investigate whether BE concentrations in peripheral blood mononuclear c ells differed in CFS and depressed patients. P-Endorphin concentrations wer e measured by radioimmunoassay in peripheral blood mononuclear cells obtain ed from 24 CFS and six depressed patients, and 16 controls. The data obtain ed indicate that BE concentrations are decreased in CFS patients when compa red with depressed patients and controls. In conclusion, peripheral blood m ononuclear cells BE concentrations could be an useful instrument in the dif ferential diagnosis between CFS and depression.