Dimethyl fumarate induces changes in B- and T-lymphocyte function independent of the effects on absolute lymphocyte count

Background: Dimethyl fumarate (DMF) is used to treat relapsing multiple sclerosis and causes lymphopenia in a subpopulation of treated individuals. Much remains to be learned about how the drug affects B- and T-lymphocytes. Objectives: To characterize changes in B- and T-cell phenotype and function induced by DMF and to investigate whether low absolute lymphocyte count (ALC) is associated with unique functional changes. Methods: Peripheral blood mononuclear cells (PBMCs) were collected from DMF-treated patients, untreated patients, and healthy controls. A subset of DMF-treated patients was lymphopenic (ALC