title: Efficient generation and characterization of tumor cell subclones with different adhesion pathways involved in cell lysis.
abstract: BACKGROUND
  Specific tumor cell recognition is required for optimal tumor directed therapy. Lymphokine activated killer (LAK) cells are able to recognize tumor targets specifically because LAK cells can distinguish between normal and tumor cells. This study was aimed at analyzing receptor molecules on tumor cells and their counter-receptor molecules on LAK cells. Cell lines which differ in the pathway by which LAK cell lysis is mediated are important for an analysis of receptor molecules.
  
  
  METHODS
  We adapted a novel method for efficient production of K562 clones in order to analyze the mechanisms by which target and effector receptor molecules mediate different LAK cell interactions. K562 cells were exposed to ethyl methanesulfonate (EMS) for mutagenization and addition of two rounds of irradiated LAK cells. Prior data demonstrated that irradiation does not effect cytolysis. Surviving cells were plated in methylcellulose and single colonies were obtained after ten days. Cells were washed, resuspended in medium, expanded and tested as targets in a 51Cr-release assay.
  
  
  RESULTS
  With this procedure a variety of clones could be generated easily and time-savingly. All twelve clones expressed the bcr/abl transcript, as determined by PCR, and were sensitive to LAK cell lysis. However, cell blockage studies revealed that K562 clones were generated with LAK cell recognition differing from parental K562. Antibody blockage showed that lysis of clone 5 (LEF 5) is partially mediated via the LFA-1/ICAM-1 pathway. ICAM-1 expression of this clone was similar to expression on K562, as determined by flow cytometry.
  
  
  CONCLUSIONS
  These clones are of great value for studying the receptor molecules involved in LAK--tumor cell interactions.
authors.affiliation: Abteilung Innere Medizin, Freie Universität Berlin, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Lefterova
authors.forename: R
authors.initials: R
authors.lastname: Negrin
authors.forename: A
authors.initials: A
authors.lastname: Neubauer
authors.forename: D
authors.initials: D
authors.lastname: Huhn
authors.forename: K
authors.initials: K
authors.lastname: Blume
authors.forename: I
authors.initials: I
authors.lastname: Schmidt-Wolf
mesh_terms: D002448:Cell Adhesion / Q000502:physiology; D016923:Cell Death / Q000502:physiology; D002999:Clone Cells; D006801:Humans; D015979:Killer Cells, Lymphokine-Activated / Q000502:physiology*; D004915:Leukemia, Erythroblastic, Acute; D014407:Tumor Cells, Cultured / Q000502:physiology*