FURTHER EVIDENCE FOR THE CLONAL NATURE OF THE IDIOPATHIC HYPEREOSINOPHILIC SYNDROME - COMPLETE HEMATOLOGICAL AND CYTOGENETIC REMISSION INDUCED BY INTERFERON-ALPHA IN A CASE WITH A UNIQUE CHROMOSOMAL ABNORMALITY

A 49-year-old man with the idiopathic hypereosinophilic syndrome (HES) and a unique chromosomal abnormality 46,XY,t(5;9)(q32;q33) is reporte d. Complete cytogenetic remission was induced by interferon alpha-2b ( IFN-alpha). The beneficial action of IFN-alpha in different stem-cell disorders such as CML, HES, multiple myeloma and solid tumours such as hypernephroma or malignant melanoma suggests a common regulatory effe ct possibly by immunomodulation or other (immune-mediated) mechanisms, but the exact pathophysiological mechanisms remain hypothetic and unr esolved. Since it, has been known for some years that the genes encodi ng for GM-CSF, IL-3 and IL-5 reside on the long arm of chromosome 5, i t could be possible that the chromosomal translocation in our patient resulted in excess production of these cytokines, hence causing the hy pereosinophilia. This case report and the results obtained from the li terature review support the growing body of evidence that IFN-alpha ha s a major place in the long-term treatment of HES, especially in those cases resistant to conventional treatment, with cytogenetic abnormali ties, or presenting as a myeloproliferative variant of HES. In those c ases IFN-alpha results in lower morbidity, lower mortality and long-te rm survival.