Detection of soluble IL-2 receptor in the serum and bone marrow of patients with minimal residual hematological malignancies: induction under therapy with IL-2

We measured the soluble IL-2 receptor alpha (sIL-2R alpha) in sera and in bone marrow of 20 patients with minimal residual hematological malignances, 6 of them with multiple myeloma (MM), 8 with Hodgkin's disease (HD) and 6 with non-Hodgkin's lymphoma (NHL), low grade. Compared to 10 normal individuals, HD and NHL group of patients had in sera significantly increased levels of sIL-2R alpha (252.8 +/- 42.9 versus 1437.2 +/- 1639 and 761.8 +/- 431 U/ml, respectively). After low-dose IL-2 given subcutaneously once daily at a dose of 1.8 x 10(6) U/patient for 3 weeks, additional significant increase in levels of IL-2R alpha was observed in sera and in bone marrow of patients with NHL (761.8 +/- 431 versus 2633 +/- 788 U/ml and 785 +/- 448 versus 2475 +/- 431 U/ml, respectively). The increase of sIL-2R alpha level after IL-2 therapy was also seen in sera and in bone marrow of HD and MM group; however, because of high standard deviation this increase was not statistically significant. We conclude that 1) in comparison to healthy subjects the levels of sIL-2R alpha remained elevated in HD and NHL patients, even at the stage of minimal residual disease (MRD) after intensive chemotherapy or radiotherapy, 2) the levels of sIL-2R alpha which appeared in sera and bone marrow of patients after IL-2 therapy seemed to be dependent on the type of hematological disorders.