ROLE OF GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR IN PHILADELPHIA (PH(1))-POSITIVE ACUTE LYMPHOBLASTIC-LEUKEMIA - STUDIES ON 2 NEWLYESTABLISHED PH(1)-POSITIVE ACUTE LYMPHOBLASTIC-LEUKEMIA CELL-LINES (Z-119 AND Z-181)

Philadelphia chromosome (Ph(1))-positive acute lymphoblastic leukemia (ALL) is a malignant disorder characterized by a poor prognosis. In re cent years hematopoietic growth factors have been used to recruit myel oid leukemia blasts into the proliferative phase of the cell cycle and as supportive agents, both with cytotoxic regimens and in the setting of bone marrow transplantation. This approach prompted us to investig ate whether myeloid growth factors have a role in Ph(1)-positive ALL. To do this, we utilized two newly established Ph(1)-positive cell line s, Z-119 and Z-181. Both lines have L2 morphology, ultrastructural cha racteristics of lymphoblasts and typical B-lineage surface markers ide ntical to those observed in the two Ph(1)-positive ALL patients from w hom they were derived. In addition, a single rearranged immunoglobulin heavy-chain gene (J(H)) band was found in both cell lines by Southern blot analysis, confirming B-cell clonality. Cytogenetic analysis of t he two lines revealed t(9; 22). Polymerase chain reaction (PCR) amplif ied cDNA from both Z-119 and Z-181 cells revealed an e(1)-a(2) BCR ABL junction, and p190(BCR-ABL) protein was detected in them by the immun e complex kinase assay. Both cell lines produce interleukin (IL)-1 bet a, granulocyte colony-stimulating factor (G-CSF) and granulocyte-macro phage CSF (GM-CSF), but neither IL-1 beta, G-CSF, their corresponding antibodies and inhibitory molecules, nor GM-CSF, affected the cell lin es' growth. However, GM-CSF neutralizing antibodies inhibited Z-181 bu t not Z-119 colony formation in a dose-dependent fashion by up to 77% and addition of GM-CSF reversed this inhibitory effect. Receptor studi es with radiolabeled GM-CSF demonstrated specific binding to Z-181 but not to Z-119 cells, and Scatchard analysis revealed that Z-181 cells express high-affinity GM-CSF receptors. Furthermore, PCR analysis show ed that Z-181 but not Z-119 bears the transcript for the GM-CSF recept or. Finally, studies using Ph(1)-positive ALL patients' marrow cells r evealed similar data. In 3 of 8 samples we detected significant concen trations of GM-CSF (7.5-13 pg/2 x 10(7) cells) and in 2 of 3 cases GM- CSF significantly stimulated Ph(1)-positive ALL colony proliferation. These data suggest that Ph(1)-positive ALL cells may produce GM-CSF, e xpress GM-CSF receptors and thus show a proliferative response to this cytokine. (C) 1996 Wiley-Liss, Inc.