Establishment and characterization of an undifferentiated human T leukemia cell line which requires...

A human leukemia cell line (TALL-101) was established from the bone marrow of a patient with an undifferentiated acute T cell leukemia using the conditioned medium (CM) of the human T cell leukemia virus (HTLV) II-transformed human cell line J-LB1. Immunofluorescence analysis on the original leukemic cells indicated the presence of T cell markers (Leu-1, Tdt, and T11); however, the established TALL-101 cell line expressed only antigens commonly present on progenitor cells, thymocytes, and myelomonocytic cells, but not on mature T cells. A high percentage of TALL-101 cells displayed the Tac antigen which was down-regulated upon incubation in the presence of recombinant human (rH) interleukin 2 (IL 2). Interferon (IFN)-gamma induced the appearance of class II histocompatibility leukocyte antigens (HLA) and of a T cell marker (3A1), and enhanced the expression of transferrin receptors on these cells. Further evidence for a T cell lineage of the TALL-101 cell line was provided by both chromosomic and genotypic analysis showing a translocation in chromosome 14 typical of T cell leukemias, and a rearrangement of the T-beta receptor locus. The growth-promoting activity in the J-LB1-CM was identified as granulocyte-macrophage colony stimulatory factor (GM-CSF), a growth factor which stimulates proliferation of normal myelomonocytic cells and other progenitor cells, but not known to have an effect on T cells. Dose response curves of [3H]thymidine incorporation and growth indicated that TALL-101 cells were sensitive to very low concentrations of rHGM-CSF, 5 ng/ml inducing maximal proliferation in chemically defined medium. The TALL-101 cell line is strictly GM-CSF-dependent for growth: upon depletion of GM-CSF from the culture medium, the cells stop proliferating immediately and die within 1 to 2 wk. The overall data, showing that GM-CSF is able to support the growth of a highly undifferentiated T cell leukemia, strongly suggests that this factor might have similar growth promoting effects on other immature T cell leukemias, and possibly, on normal T cell progenitors.