Pilot Study of Natural Killer Cells in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis and Multiple Sclerosis.

PILOT projects; KILLER cells; CHRONIC fatigue syndrome; MULTIPLE sclerosis; CELL-mediated cytotoxicity

Patients with chronic fatigue syndrome/myalgic encephalomyelitis ( CFS/ ME) and multiple sclerosis ( MS) suffer from debilitating fatigue which is not alleviated by rest. In addition to the fatigue-related symptoms suffered by patients with CFS/ ME and MS, dysfunction of the immune system and, in particular, reduced natural killer ( NK) cell cytotoxic activity has also been reported in CFS/ ME and MS. The purpose of this pilot study was to compare NK cellular mechanisms in patients with CFS/ ME and MS to investigate potential dysfunctions in the NK cell activity pathway. Flow cytometry protocols assessed CD56dim CD16+ and CD56bright CD16+/− NK cell expression of adhesion molecules, NK activating and inhibiting receptors, NK cell maturation and lytic proteins. All participants in this study were female and included 14 patients with CFS/ ME, nine patients with MS and 19 non-fatigued controls. The patient groups and the non-fatigued controls were not taking any immunosuppressive or immune-enhancing medications. In the MS cohort, KIR2 DL5 was significantly increased on CD56bright CD16+/− NK cells and expression of CD94 was significantly increased on CD56dim CD16+ NK cells in comparison with the controls. Co-expression of CD57 and perforin was significantly increased on CD56dim CD16+ NK cells from patients with CFS/ ME compared to the MS and non-fatigued control participants. The results from this pilot study suggest that NK cells from patients with CFS/ ME and MS may have undergone increased differentiation in response to external stimuli which may affect different mechanisms in the NK cell cytotoxic activity pathway. [ABSTRACT FROM AUTHOR]