AML BLASTS VARIABLY EXPRESS INTERLEUKIN-2 RECEPTOR-ALPHA-CHAINS, BETA-CHAINS OR GAMMA-CHAINS WITHOUT MEASURABLE EFFECTS ON PROLIFERATION, CYTOKINE MESSAGE EXPRESSION OR SURFACE EXPRESSION OF ADHESION MOLECULESUPON STIMULATION WITH INTERLEUKIN-2

Preliminary clinical studies including interleukin 2 (IL-2) in chemoth erapy strategies for treatment of acute myeloblastic leukemia (AML) su ggest that IL-2 may improve the disease-free survival of the patients. Because of reports showing interleukin 2 receptor expression on AML b lasts, it is important to know whether IL-2 may directly influence the se leukemic cells. In initial studies using flow cytometry to analyze surface expression of interleukin 2 receptors (IL-2R), we found expres sion of the IL-2R alpha chain on blast cells in 26% and of the IL-2R b eta-chain in 81% of the patients. To confirm these results at the tran scriptional level, we studied the expression of RNA of the IL-2R alpha , beta, and gamma chains by RT-PCR in the bone marrow of 38 newly diag nosed patients with AML and in three AML-derived cell lines, RNA of th e alpha chain was detectable in 11/38 patients, the beta chain in 10/3 8 patients and the gamma chain in 30/38 patients with AML. Blast cells obtained from colonies growing in semisolid media expressed mRNA for IL-2R. RNA for all three IL-2R chains was expressed in lines KG1, HEL 99.1.7 and K562. In comparison with unstimulated cell lines, incubatio n of the three lines with various amounts of IL-2 over 3 and 14 days d id not increase their growth or change message expression of IL-2R, IL -10, and TGF-beta and surface expression of the adhesion molecules CD 11, CD 18, CD 29 and CD 54. In conclusion, despite expression of IL-2 receptors, AML blasts do not respond to IL-2 by proliferation, message expression for various cytokine genes and surface expression of cellu lar adhesion molecules.