Background: A soluble form of interleukin-2 receptor(sIL-2R) is released from activated T cells. Serum sIL-2R levels are elevated in some hematological malignancies
and could be used to assess disease activity and prognosis.
Material and Methods: To define clinical usefulness and significance as a marker predicting disease progress in chronic myeloprolifsrative disorders, the serum levels of
sIL-2R were measured in 40 cases of chronic myelogenous leukemia(CML; 25 chronic phase, 7 accelerating phase, 8 blastic phase), 3 cases of polycythemia vera(PV), 5 cases
of essential thrombocythemia(ET) and 4 cases of idiopathic myelofibrosis(MF) and in 37 cases of healthy subjects using sandwich enzyme immunoassay.
Results: Serum sIL-2R levels in the patients of CML, PV, ET, and MF were higher compared with the normal healthy controls. In CML, serum sIL-2R levels in the patients
of blastic and accelerating phases were significantly higher than those of chronic phase. In CML of chronic phase, serum sIL-2R levels at diagnosis were related to WBC count but not to other clinical and hematologic paramaters. The leukemic cells of one patient with lymphoblastic phase of CML expressed IL-2R(CD25). Among 4 patients of CML with sIL-2R levels above 2,000U/mL at diagnosis, transformation to blastic crisis was noted in 3 patients and 2 patients died within 1 year after diagnosis. But among 11 patients of CML with sIL-2R levels below 2,000U/mL at diagnosis, only 2 patients experienced blastic crisis and died within 1 year after diagnosis.
Conclusion: This study indicated that serum sIL-2R levels were high in chronic myeloproliferative disorders, and that increasing levels of serum sIL-2R might be useful
to predict disease progress. Further studies including more patients and longer follow-up may substantiate serum sIL-2R as a prognostic indicator in CML.

Keywords: Serum sIL-2R, Chronic myeloproliferative disorders, Chronic myelogenous leukemia,