LAUSR

OBJECTIVE Treatment with dimethyl fumarate (DMF) leads to lymphopenia and infectious complications in a subset of patients with multiple sclerosis (MS). Here, we aimed to reveal immune markers of DMF-associated lymphopenia. METHODS This prospective observational study longitudinally assessed 31 individuals with MS by single-cell mass cytometry before, and after 12 and 48 weeks of DMF therapy. RESULTS Employing a neural network-based representation learning approach, we identified a CCR4-expressing T helper cell population negatively associated with relevant lymphopenia. INTERPRETATION CCR4-expressing T helper cells represent a candidate prognostic biomarker for the development of relevant lymphopenia in patients undergoing DMF treatment. This article is protected by copyright. All rights reserved.