Allogeneic blood stem cell transplantation following non-myeloablative conditioning for hypereosinophilic syndrome.

A male patient with hypereosinophilic syndrome (HES) underwent an allogeneic blood stem cell transplantation from a female donor following non-myeloablative conditioning consisting of a 2 Gy dose of TBI and fludarabine 30 mg/m(2) intravenously on three days. Before transplantation 100% of the mitotic bone marrow cells of the patient showed a clonal karyotype abnormality. Three months after the transplantation eosinophilia had resolved and a chromosome analysis revealed normal female karyotype. The present study shows that stem cell transplantation after non-myeloablative conditioning may have curative potential for HES.