A 23-year-old man first visited a local hospital in 1998 because of exertional
dyspnea. Peripheral blood examination revealed mild
leukocytosis with 82% eosinophils, and he was treated with
prednisolone. As the
eosinophilia did not improve, he was referred to Tokai University Hospital in March 1999 for further diagnosis and treatment. The patient was diagnosed as having
hypereosinophilic syndrome (HES) because of unexplained
hypereosinophilia persisting for more than 6 months, resulting in cardiac dysfunction. His disease was progressive in spite of immunosuppressive therapy,
interferon-alpha and cytotoxic
chemotherapy. Since he had an HLA-identical brother, allogeneic
bone marrow transplantation (BMT) was performed in October 1999. After completion of the immunosuppressive therapy on day 79 after BMT, the number of eosinophils gradually increased again. Although we suspected recurrence of the disease, DNA fingerprinting revealed that the peripheral granulocytes were 100% donor type. An increase of
interleukin-5 (IL-5) produced by peripheral lymphocytes and a decrease of the Th1/2 ratio suggested that the
eosinophilia was related to GVHD. The
eosinophilia was eventually controlled by
cyclosporin. We conclude that DNA fingerprinting and examination of the
IL-5 level and Th1/2 ratio are useful for differentiating between relapse and GVHD in cases of
eosinophilia occurring after BMT for HES.