Altered functional B cell subset populations in patients with chronic fatigue syndrome compared to healthy controls

Chronic fatigue syndrome (CFS) is a heterogeneous disorder of unknown aetiology characterized by disabling fatigue, headaches, sleep disturbance and several other symptoms. The onset of CFS may follow a viral infection or period of stress. Patients with CFS do not have hypogammaglobulinaemia, predisposition to recurrent bacterial infections or symptoms of autoimmunity. To date, defects in B cell numbers or function have not been shown in the literature. However, treatment with anti-B cell therapy using Rituximab has recently shown benefit to CFS patients. We therefore postulated that patients with CFS had a subtle humoral immune dysfunction, and performed extended B cell immunophenotyping. We undertook a detailed characterization of the proportions of the different B cell subsets in 33 patients with CFS fulfilling the Canadian and Fukada criteria for CFS and compared these with 24 age- and gender-matched healthy controls (HC). CFS patients had greater numbers of naive B cells as a percentage of lymphocytes: 6 center dot 3 versus 3 center dot 9% in HC (P=0 center dot 034), greater numbers of naive B cells as a percentage of B cells: 65 versus 47% in controls (P=0 center dot 003), greater numbers of transitional B cells: 1 center dot 8 versus 0 center dot 8% in controls (P=0 center dot 025) and reduced numbers of plasmablasts: 0 center dot 5 versus 0 center dot 9% in controls (P=0 center dot 013). While the cause of these changes is unclear, we speculate whether they may suggest a subtle tendency to autoimmunity.