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Serum interleukin-2 (IL-2), soluble IL-2 receptors (sIL-2R) and tumor necrosis factor-alfa (TNF-alpha) levels were determined in 66 previously untreated consecutive patients with acute myeloid leukemia (AML) and in 22 normal volunteers. The following mean (+/- SE) values were observed in patients and controls, respectively: 35 +/- 14.7 (range 0.5-500) and 0.7 +/- 0.02 (0.5-0.8 U/ml for IL-2 (p = 0.001); 1622 +/- 289 (110-10,600) and 422 +/- 30 (207-666) U/ml for sIL-2R (p = 0.0001); 1247 +/- 196 (218-4672) and 152 +/- 11 (75-308) pg/ml for TNF-alpha (p = 0.0001). With respect to the FAB classification system, we found a significantly different distribution of serum IL-2 mean values in distinct subcategories, i.e. 3.4 +/- 1.9 U/ml in M1-M2-M3 and 42.4 +/- 20.4 U/ml in M4-M5 subgroups, respectively (p = 0.01), whereas sIL-2R and TNF-alpha levels were 1144 +/- 322 U/ml and 1120 +/- 317 pg/ml in M1-M2-M3 patients and 1945 +/- 317 U/ml and 1270 +/- 259 pg/ml in the M4-M5 group. A significantly positive correlation between TNF-alpha and sIL-2R (r = 0.53; p = 0.002) was also detected in the M4-M5 group. Sixty-three out of 66 patients received an intensive chemotherapy program. Univariate analysis showed that age and sIL-2R greater than 2000 U/ml significantly affected both complete remission rate and overall survival, whereas by multivariate analysis, age was the only independent variable significantly influencing survival. These data confirm recent in vitro evidence suggesting the role of IL-2, sIL-2R, and TNF-alpha in the control of normal hematopoiesis and leukemogenesis. Since the availability of recombinant cytokines for clinical use in AML, it is crucial to understand their spectrum of interaction in order to select the appropriate combination for in vivo administration.

In this study we analysed serum IL-2 levels in 61 patients with multiple myeloma (MM). Patients serum IL-2 levels were significantly higher than normal controls. Moreover, higher serum IL-2 levels were associated with a prolonged actuarial survival. In particular, 87% of the MM patients with IL-2 greater the or equal to 10 U/ml are still alive at 5 years while only 13% of the remaining patients with IL-2 less than 10 U/ml are alive. The multivariate analysis confirmed these data indicating that high serum IL-2 levels are the most useful predictor index of longer survival in MM patients. Furthermore, among the 50 patients in whom serum beta-2-microglobulin (SB2M) determination was available we observed that all patients with serum IL-2 levels greater than or equal to 10 U/ml had SB2M less than 6 micrograms/ml, whereas in patients with serum IL-2 less than 10 U/ml SB2M ranged from 1.3 to 15 micrograms/ml. Using these two parameters we were able to identify three groups of patients with different survival duration. Group A (9 patients) defined by serum IL-2 greater than or equal to 10 U/ml and SB2M less than 6 micrograms/ml in which all patients are alive: group B (26 patients) characterized by serum IL-2 less than 10 U/ml and SB2M less than 6 micrograms/ml in which 24% of patients are alive and group C (15 patients) characterized by serum IL-2 levels less than 10 U/ml and SB2M greater than or equal to 6 micrograms/ml in which the actuarial survival curve drops to 0 at 2.5 years. A statistically significant difference was observed between groups A and B (P less than 0.05), groups A and C (P less than 0.01) and groups B and C (P less than 0.01). These data could reflect the existence of an active T cell control on B cell neoplasia and may suggest the opportunity of a more extensive use of recombinant biological modifiers such as IL-2 in the therapeutic strategy of MM.