We evaluated the in vitro proliferative response to exogenous IL-1β in terms of tritiated thymidine (3H-TdR) incorporation in leukemic cells obtained from 119 patients with various types of acute leukemia. The content of IL-1β in leukemic cells was measured by enzyme-amplified sensitivity immunoassay. We observed a significant proliferative response to exogenous IL-1β in leukemic cells from 27 66 patients with de novo AML, 1 29 patients with ALL, 2 3 patients with AUL, 8 12 patients with AML arising from MDS, 4 7 patients with myeloid crisis of CML, and 0 4 patients with lymphoid crisis of CML. Proliferation was marked in myeloid leukemic cells of a more premature stem cell origin. There were no significant differences in proliferative responses among the different FAB classes of de novo AML. The IL-1β content of leukemic cells was low in patients with lymphoid leukemia, but there was no significant difference among the various types of myeloid leukemia. There was no correlation between the proliferative response to exogenous IL-1β and the IL-1β content of leukemic cells. When we correlated the proliferative response to exogenous IL-1β with treatment outcome in patients with de novo AML, we found the rate of complete remission (CR) to be lower in those with a high proliferative response. We noted a longer duration of CR (p = 0.07) and of survival (p < 0.05) in patients with a low proliferative response. Thus, a high proliferative response to IL-1β in the cells of AML patients may indicate a poor prognosis.
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