Amelioration of ongoing experimental autoimmune encephalomyelitis with fluoxetine

In patients with multiple sclerosis, the selective serotonin reuptake inhibitor, fluoxetine, resulted in less acute disease activity. We tested the immune modulating effects of fluoxetine in a mouse model of multiple sclerosis, i.e. experimental autoimmune encephalomyelitis (EAE). We show that fluoxetine delayed the onset of disease and reduced clinical paralysis in mice with established disease. Fluoxetine had abrogating effects on proliferation of immune cells and inflammatory cytokine production by both antigen-presenting cells and T cells. Specifically, in CD₄ T cells, fluoxetine increased Fas-induced apoptosis. We conclude that fluoxetine possesses immune-modulating effects resulting in the amelioration of symptoms in EAE.