ESTABLISHMENT AND CHARACTERIZATION OF A NEW, FACTOR-INDEPENDENT ACUTEMYELOID-LEUKEMIA LINE DESIGNATED EI501

We established a factor-independent acute myeloid leukemia cell line, designated Ei501. The line has been growing in RPMI 1640 media for 18 months and can be maintained without addition of growth factors. Ei501 is positive for myeloperoxidase and negative for esterase and PAS. Cy togenetic analysis revealed the FAB M3 associated t(15;17) translocati on and a translocation of the chromosomes 7 and 8: 46 XX, -7, +t(7;8)( q32;q13), t(15;17)(q22;q12). This karyotype was confirmed by fluoresce nce in situ hybridization. Ei501 cells express AML-associated surface markers such as CD13, CD33 and CD38. Although 42% of the patient's bla st cells were CD34-positive, the line lacks surface expression of CD34 . Furthermore the line has a number of characteristics which are detec table in blasts from AML patients, such as surface adhesion molecules, cytokines such as TGF-beta, cytokine receptors such as the IL-2 recep tor beta and gamma chains or the IL-4 receptor and the genes for the t ranscription factor wt-1 (Wilms' tumor gene) and for the proto-oncogen e bcl-2, both shown to be present in the majority of patients with AML . Additionally the line can be used as target in cytotoxicity assays u sing IL-2 activated cytotoxic lymphocytes as effector cells. In conclu sion, besides a rare karyotype the Ei501 cell line has several feature s common in AML, and may therefore be used as a model to study pathoge netic mechanisms in acute myeloid leukemia.