title: Cell fusion in tumor progression: the isolation of cell fusion products by physical methods.
abstract: BACKGROUND
  Cell fusion induced by polyethylene glycol (PEG) is an efficient but poorly controlled procedure for obtaining somatic cell hybrids used in gene mapping, monoclonal antibody production, and tumour immunotherapy. Genetic selection techniques and fluorescent cell sorting are usually employed to isolate cell fusion products, but both procedures have several drawbacks.
  
  
  RESULTS
  Here we describe a simple improvement in PEG-mediated cell fusion that was obtained by modifying the standard single-step procedure. We found that the use of two PEG undertreatments obtains a better yield of cell fusion products than the standard method, and most of these products are bi- or trinucleated polykaryocytes. Fusion rate was quantified using fluorescent cell staining microscopy. We used this improved cell fusion and cell isolation method to compare giant cells obtained in vitro and giant cells obtained in vivo from patients with Hodgkin's disease and erythroleukemia.
  
  
  CONCLUSIONS
  In the present study we show how to improve PEG-mediated cell fusion and that cell separation by velocity sedimentation offers a simple alternative for the efficient purification of cell fusion products and to investigate giant cell formation in tumor development.
authors.affiliation: Department of Internal Medicine IRCCS Policlinico San Matteo, viale Golgi 19, Pavia 27100 Italy and University of Pavia, Strada Nuova, Pavia 27100; Italy. gmas0877@yahoo.com.
authors.forename: Filippo
authors.initials: F
authors.lastname: Pedrazzoli
authors.forename: Iraklis
authors.initials: I
authors.lastname: Chrysantzas
authors.forename: Luca
authors.initials: L
authors.lastname: Dezzani
authors.forename: Vittorio
authors.initials: V
authors.lastname: Rosti
authors.forename: Massimo
authors.initials: M
authors.lastname: Vincitorio
authors.forename: Giammaria
authors.initials: G
authors.lastname: Sitar