Clinical importance of interleukin-2 receptor alpha-chain expression in acute leukemia. The Japan Cooperative Group of Leukemia/Lymphoma.

To clarify the clinical importance of interleukin-2 (IL-2) receptor (IL-2R) expression in acute leukemia, we examined 517 adult patients with acute leukemia and CML blast crisis (CML-BC). IL-2R alpha was expressed in 42/311 AML, 5/11 acute unclassified leukemia, 24/116 pre-B ALL, 2/32 T-ALL, and 27/47 CML-BC, while IL-2R beta was expressed only in 2 T-ALL. Expression of IL-2R alpha was closely associated with that of different lineage markers, CD11b, CD34, and Ph1+ abnormality. IL-2R alpha(+) non-T leukemic cells did not respond to IL-2. Clinical outcome of IL-2R alpha (+) leukemia showed lower response to conventional chemotherapy and poorer prognosis than IL-2R alpha (-) cases. Serum IL-2R alpha level in IL-2R alpha (+) cases increased at the onset. Our findings indicate the diagnostic importance of IL-2R alpha expression in acute leukemia as a prognostic risk factor with a close relation to the particular cellular characteristics.