Background: The role of T cell subpopulations and their ability to produce immunoregulatory cytokines has been extensively studied in multiple sclerosis (MS). However, the exact mechanisms by which T cells and cytokines contribute to disease activity remain to be clarified.
Objectives: To analyze the longitudinal relation between markers of T cell activation and differentiation and disease activity in MS patients.
Methods: During a period of 9 months, clinical disease activity was scored, monthly MRI scans were performed, and blood was taken for immune measurements in a group of 13 untreated clinically definite MS patients.
Results: Disease activity, as measured by the occurrence of active MRI lesions, is associated with a significant transient decrease in both T cells producing interferon-gamma (IFN-gamma) and T cells producing interleukin (IL)-4.
Conclusions: Our results suggest that MRI-documented disease activity is associated with a transient decrease in circulating cytokine producing T cells, possibly due to the migration of activated T cells into the CNS.