Humoral and cellular immune response after influenza vaccination in patients with postcancer fatigue and patients with chronic fatigue syndrome.

9070 Background: Postcancer fatigue (PCF) is a frequently occurring problem, impairing quality of life. Patients with chronic fatigue syndrome (CFS) also suffer from severe fatigue symptoms. We hypothesized that in fatigued patients (PCF and CFS) alterations in immune response could explain fatigue symptoms. Therefore, we examined whether the humoral and/or cellular immune response after influenza vaccination differed between fatigued patients and non-fatigued individuals and between PCF and CFS patients. Methods: PCF (n=15) and CFS patients (n=22) were vaccinated against influenza. Age and gender matched non-fatigued cancer survivors (n=12) and healthy controls (n=23) were included for comparison. Antibody responses were measured at baseline and at day 21 by a hemagglutination inhibition test. T cell responses were measured at baseline and at day 7 by a lymphocyte proliferation and activation assay. Results: Both patient groups developed seroprotection rates comparable to the accompanying control groups. Functional T cell reactivity was observed in all groups. Proliferation at baseline was significantly lower in fatigued patients compared to non-fatigued individuals. A significant increase in proliferation from baseline to day 7 was observed in fatigued patients, but not in controls. At day 7, proliferation was not significantly different between fatigued patients and non-fatigued individuals. CD4+CD127-FoxP3+ expression was significantly higher in PCF patients compared to non-fatigued cancer survivors. Conclusions: We observed a lower T cell proliferation at baseline in fatigued patients compared to non-fatigued individuals, suggesting a difference in the baseline state of the immune system between fatigued patients and non-fatigued individuals. Furthermore, the difference in CD4+CD127-FoxP3+ expression between PCF and CFS patients suggests subtle differences in immune state between these two fatigued patient groups. However, since humoral and cellular immune responses after vaccination did not differ significantly between fatigued patients and non-fatigued individuals, vaccination of fatigued patients (PCF and CFS) can be effective.