EMBARGOED FOR RELEASE UNTIL 4 PM ET, April 08, 2002
Study Confirms Seasonal Fluctuation in Immunity-generating Cells Among MS Patients
St. Paul, Minn. -
Through a first-ever longitudinal study, researchers have confirmed that T-cells (white blood cells that fight infection and disease in healthy individuals) show seasonal fluctuation in multiple sclerosis (MS) patients, and that the T-cells were at a high in the autumn months. The study is published in the April 9 issue of Neurology, the scientific journal of the American Academy of Neurology. The finding that seasonal changes affect the immune system is important for people with MS since there is strong evidence that through the disease, a person''s own immune system attacks the central nervous system. "It is clear that activated T-cells play an important role in MS disease activity. However, the triggering cause is still largely unknown," said study author, Joep Killestein, MD, VU Medical Center in Amsterdam, The Netherlands. "Viral infections are more common in particular seasons and may be a possible explanation of the fluctuations of immunological and radiological effects in MS." Twenty-eight patients with either relapsing-remitting or secondary progressive MS participated in the study at the Amsterdam facility. Twelve blood samples were collected from each patient during 18 months of follow-up observations. The patients were also tested using magnetic resonance imaging (MRI) to determine any changes in lesions. "Even though clear fluctuations were observed, no significant seasonal variation could be detected in the number of MRI lesions nor in the number of patients experiencing relapses," according to Killestein. Killestein pointed out that while T-cells were more activated during the autumn months, as measured by the production of cytokines (soluble molecules which mediate interactions between immune cells), there was not a discernable change in the lesions in the brain which are inherent with MS. This was the first study that set out to analyze longitudinal effects as well as seasonal variations among a group of relapsing-remitting and secondary progressive MS patients, said Killestein. According to the American Academy of Neurology, MS is a disabling neurological disorder that involves inflammation within the central nervous system (the brain and spinal cord) followed by the loss of protective myelin sheaths that surround nerve fibers. As the result of the inflammatory process, lesions (called plaques) develop in the brain and spinal cord. Symptoms like numbness or tingling, weakness or unsteady gait may go away or may remain after an attack. For individuals with progressive forms of MS, these symptoms may gradually worsen over time without rapid or abrupt changes.