title: Synergistic action of interleukin-2 and Steel factor (SLF) on a human T lymphoblastoid cell line.
abstract: Ten cell lines recently established from paediatric patients with acute lymphoblastic leukaemia (ALL) were examined for expression of P145c-kit, the growth factor receptor encoded by the c-kit proto-oncogene, by immunofluorescence and flow cytometry using monoclonal antibody YB5.B8. Three of five T-ALL cell lines, but none of five B lineage ALL cell lines displayed significant binding of the antibody. The cell line with the highest level of binding was PER-423 (Kees et al, Leukemia Res 1993; 17: 51-59 which has the phenotype CD7+, CD56bright, CD2-, CD4-, CD5-, CD8-, CD16-, has rearranged T cell receptor beta-chain genes, expresses cytoplasmic CD3 and is strictly dependent on interleukin 2 (IL-2) for proliferation. Recombinant to act in synergy with IL-2 to promote proliferation of PER-423 cells. In five experiments, SLF increased the maximal amount of proliferation by 105 +/- 15%, and decreased the level of IL-2 required for a half-maximal response by 43 +/- 7%. The cells constitutively express the intermediate affinity IL-2 receptor (beta/gamma), but can be induced in the presence of phorbol ester to express the alpha chain (CD25, Tac) which confers high affinity binding of IL-2. In contrast, the alpha chain was not induced by SLF. The enhancement of proliferation of PER-423 cells by SLF could be prevented by inclusion in the assay of a blocking monoclonal antibody to P145c-kit. These experiments demonstrate that SLF/P145c-kit can provide a significant growth stimulus for ALL cells, and PER-423 cells may be a useful system for investigating the mechanism of synergy between SLF and IL-2.
authors.affiliation: Division of Children's Leukaemia and Cancer Research, Princess Margaret Hospital, West Perth, WA, Australia.
authors.forename: U R
authors.initials: UR
authors.lastname: Kees
authors.forename: L K
authors.initials: LK
authors.lastname: Ashman
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D002648:Child; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005455:Fluorescent Antibody Technique; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology*; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma; D000090063:Proto-Oncogene Mas; D019089:Stem Cell Factor; D013601:T-Lymphocytes; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D015815:Cell Adhesion Molecules; D016298:Hematopoietic Cell Growth Factors; D007376:Interleukin-2; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D019089:Stem Cell Factor