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Supplemental data at Neurology.org/nn Immunologic and MRI markers of the therapeutic effect of IFN-b-1a in relapsing-remitting MS Objectives: To assess potential roles of effector cells and immunologic markers in demyelinating CNS lesion formation, and their modulation by interferon b-1a (IFN-b-1a). Methods: Twenty-three patientswith relapsing-remittingmultiple sclerosis (RRMS) received IFN-b-1a for 6months. Immunologic marker results were correlated with brainMRI lesion volumes, and volumes of normal-appearing brain tissue (NABT) with decreasing or increasing voxel-wisemagnetization trans-fer ratio (VW-MTR), suggestive of demyelination and remyelination, respectively. Results: Baseline expression of Th22 cell transcription factor aryl hydrocarbon receptor (AHR) and interleukin (IL)-17F, and percentages of IL-22–expressing CD41 and CD81 cells, were signifi-cantly higher in patients vs 15 healthy controls; IL-4 in CD41 cells was lower. Baseline percent