Plasma CXCL5, but not CCL2 or CXCL10, levels increase in association with new MS lesion formation. Patients with relapsing MS were classified as having “active” or “inactive” disease based on clinical course, neurological examination, and MRI scanning. Plasma levels of CXCL5, CCL2, and CXCL10 were measured by multiplex assay. Patients with active disease had enhancing MRI lesions and patients with inactive disease had no enhancing lesions on the day of phlebotomy. Box plots show median, interquartile range, sample minimum, and maximum. Circles show outliers.