Granulocyte macrophage colony-stimulating factor treatment of a patient in myasthenic crisis: Effects on regulatory T cells

Introduction: In this study we describe a patient with a prolonged myasthenic crisis refractory to conventional immunomodulatory therapy who was treated with GM-CSF (granulocyte macrophage colony-stimulating factor, sargramostim). Methods: T-regulatory cell (Treg) suppressive function and Foxp3 expression were evaluated before and after treatment with GM-CSF. Results: Treatment with GM-CSF was associated with clinical improvement, expansion in the circulating numbers of Foxp3+ cells, increase in Foxp3 expression levels in Tregs, early improvement in Treg suppressive capacity for AChR-ainduced T-cell proliferation, and subsequent enhancement in Treg suppression of polyclonal T-cell proliferation. Conclusion: Although definitive conclusions cannot be drawn from a single case, the correlation with similar findings in GM-CSFtreated animals with experimental autoimmune myasthenia gravis suggests further exploration of the effects of GM-CSF in myasthenia gravis should be studied in a clinical trial setting. Muscle Nerve 46: 449453, 2012