Establishment and characterization of two novel cytokine-responsive acute myeloid and monocytic leukemia cell lines, MUTZ-2 and MUTZ-3.

Human permanent leukemia cell lines represent powerful research tools in a multitude of investigations. The two new continuous leukemia cell lines MUTZ-2 and MUTZ-3 were derived from the peripheral blood of patients with acute myeloid leukemia (AML) FAB M2 and AML FAB M4. MUTZ-2 and MUTZ-3 cells have morphological and immunophenotypical features of myeloid and monocytic cells, respectively. While MUTZ-2 is negative, MUTZ-3 cells express the monocytic surface marker CD14, albeit weakly. The monocytic nature of MUTZ-3 cells is underlined by the expression of the monocyte-specific esterase (MSE), myeloperoxidase (MPO) and tartrateresistant acid phosphatase (TRAP) enzymes; MUTZ-2 is negative for MSE and TRAP, but expresses MPO. For sustained cell growth, both cell lines require constitutively the addition of cytokines to the culture medium and retain an absolute dependence on conditioned medium or recombinant growth factors for proliferation and survival. Incubation with single recombinant cytokines from a broad spectrum of growth factors established that the strongest proliferation response of MUTZ-2 cells was elicited by FLT-3 ligand, granulocyte colony-stimulating factor (G-CSF), macrophage CSF (M-CSF), interferon-gamma (IFN-gamma) and stem cell factor (SCF), whereas granulocyte-macrophage CSF (GM-CSF), M-CSF, interleukin-3 (IL-3) and SCF were the most effective growth factors in inducing proliferation of MUTZ-3. Both cell lines were proliferatively responsive to several further cytokines, however, to a lesser extent. Exposure to phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or the physiological all-trans retinoic acid (ATRA) had growth-inhibitory and differentiation-inducing effects on both cell lines. Using a clonogenic cell recovery assay, both cell lines were found to be sensitive to the chemotherapeutic drugs cytosine arabinoside (Ara-C) and daunorubicin (DNR), MUTZ-2 cells being more sensitive to both Ara-C and DNR treatment than MUTZ-3 cells. Chromosomal trisomies 8 and 10 were found in MUTZ-2 cells without any additional structural abnormalities. MUTZ-3 carries the rare, but recurrent AML-associated translocation (12;22)(p13;q11-q12) reflecting the karyotype of the original tumor. The main characteristics of these cell lines remained the same during about 1 year of continuous culture as well as after freezing and thawing. In summary, we established and characterized two new leukemia cell lines with myeloid or monocytic features which are growth factor-responsive, one of them carrying a unique chromosomal translocation. These cells will be of particular value for investigating the complex cytokine network and molecular events caused by chromosomal aberrations.