Apr 19, 2002
NEW YORK (Reuters Health)
Seasonal variation in immune function and MRI markers of disease activity in multiple sclerosis (MS) suggest that there is an environmental role in T-cell activation, according to a report in the April 9th issue of Neurology.
"Recently, the results of cross-sectional studies suggested seasonal variation of both interferon (IFN)-gamma production and the number of active MRI lesions in MS," Dr. J. Killestein, of VU Medical Center, Amsterdam, The Netherlands, and colleagues note. To confirm this and to investigate correlations, they analyzed data from 28 MS patients who had undergone detailed longitudinal monitoring of immune function and MRI measurements.
"Significant seasonal variation was observed in T-cell activation as measured by the ability of T-cells to secrete the pro-inflammatory cytokines tumor necrosis factor-alpha and IFN-gamma," the investigators explain. "Maximum values were found in samples obtained during autumn."
While the team observed clear fluctuations, they did not observe significant seasonal variation in active MRI lesions. In addition, no seasonal differences were observed in the number of patients who had clinical relapses.
There were no significant correlations between fluctuations in immune measurement and active MRI lesions. However, there was a weak correlation between fluctuations of in vitro IFN-gamma secretion and active MRI lesions (p = 0.082).
Dr. Killestein and colleagues discuss various possible reasons for the seasonal variations. They note that changes in viral infection rates have been suggested, but say "our patient group was not systematically studied for viral and other infections during the trial."
© 2002 Reuters Ltd