Immunology

Natural killer cell (NK) function in a prospective cohort of adolescents with CFS compared to controls following infectious mononucleosis (IM) was discussed by B.Katz (Chicago, USA). He felt the study was important because NK function has been much studied and results are not always consistent. 9 with CFS and 9 matched controls were studied. Blood was taken at 6, 12 and 24 months following IM.  NK quantification and function was measured. There was no difference in NK cell numbers at each of the 3 points of analysis compared to controls. However NK cell function was higher in cases than controls at 6 months, with less differential at 12 and 24 months. The conclusion was that there was no decrease in NK cell function in this group.

However, E.Brenu (Gold Coast, Australia) looked at cytotoxic function of NK-cells and CD8+T cells in CFS, and her findings showed significant decreases in cytotoxic activity compared to controls at baseline, at 6 and 12 months. NK CD56 bright cells remained decreased in those with CFS. The study confirmed reduced immune function in CFS, and she highlighted the possibility that NK-cell cytotoxic function could be a potential biomarker.

Her second study assessed proteins and receptors secreted and expressed by CD4+T lymphocytes over time. At baseline IL-10, TNFα and IFNγ were increased in the CFS group. At 6 months, IL-2 was increased and IL-10 and IL-!7a were significantly decreased in the  CFS group, and at 12 months only IL-2 was significantly increased in the CFS group. The results suggest that the cytokine profile in CFS changes over time during disease progression. Experimental findings need to be matched with data on clinical disease progression.

The objectives of a study presented by V.Falkenberg (Atlanta, USA) were to determine the pattern of perforin gene methylation in conjunction with gene expression, and whether these features were altered in CFS. Increased promoter DNA methylation correlated with reduced perforin expression in the non-fatigued group, the relationship was not seen in CFS. Small but significant differences in methylation were detected over the day and there were differences between both groups. Further studies are needed to help explain and understand these differences.

N.Klimas (chairing this session) pointed out the importance of these papers in helping us understand the nature of the immune response and the variations over time.