title: ATG-Fresenius inhibits blood circulating cell proliferation in a dose-dependent manner: an experimental study.
abstract: BACKGROUND
  Antithymocyte globulin (ATG)-Fresenius (Neovii-Biotech, Graefelfing, Germany), a highly purified rabbit polyclonal antihuman T-lymphocyte immunoglobulin resulting from immunization of rabbits with the Jurkat T-lymphoblast cell line, is currently used for the prevention of acute rejection in patients receiving solid organ transplants. Our aim was to investigate the in vitro activity of ATG-Fresenius regarding the proliferation of peripheral blood mononuclear cells (PBMCs), an important mechanism of rejection after solid organ transplantation.
  
  
  METHODS
  PBMCs were isolated from 6 healthy donors. Proliferation was assayed using [(3)H] thymidine incorporation. For analysis of mitogen-stimulated proliferation, the PBMCs were incubated at 37°C with various concentrations of ATG-Fresenius in the absence/presence of 40 μg/mL phytohemagglutinin. For analysis of the mixed lymphocyte reaction, PBMCs were incubated at 37°C with various concentrations of ATG-Fresenius for 3 days. On day 3, PBMCs (stimulator cells) from allogeneic donors were incubated with 25 μg/mL mitomycin C. The responder cells (preincubated with ATG-Fresenius) were then cultured at 37°C with the stimulator cells for 6 days. Groups were compared using ANOVA and the Tukey-Kramer multiple comparison test.
  
  
  RESULTS
  Preincubation of PBMCs with ATG results in concentration-dependent inhibition of phytohemagglutinin-stimulated proliferation. The effect was more pronounced after 2 and 3 days of treatment with ATG compared with 1 day. There was a concentration-dependent decrease in the mixed lymphocyte reaction-induced proliferation (up to 80%) at ATG-Fresenius concentrations as low as 0.05 to 0.5 μg/mL. No further effect on proliferation at ATG-Fresenius concentrations of 0.5 to 50 μg/mL was seen, and higher concentrations (>100 μg/mL) totally inhibited proliferation.
  
  
  CONCLUSIONS
  Our in vitro results provide more evidence of the beneficial effect of ATGs in the early phase of solid organ transplantation, by reducing effector cell proliferation.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, University Hospital Frankfurt, Goethe University, Frankfurt/Main, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Werner
authors.affiliation: Neovii Biotech GmbH, Gräfelfing, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Seitz-Merwald
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, University Hospital Frankfurt, Goethe University, Frankfurt/Main, Germany.
authors.forename: A H
authors.initials: AH
authors.lastname: Kiessling
authors.affiliation: Department of Cardiac Surgery, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Kur
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, University Hospital Frankfurt, Goethe University, Frankfurt/Main, Germany. Electronic address: Andres.Beiras@kgu.de.
authors.forename: A
authors.initials: A
authors.lastname: Beiras-Fernandez
mesh_terms: D000961:Antilymphocyte Serum / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology / Q000502:physiology; D007959:Lymphocyte Culture Test, Mixed
chemical_list: D000961:Antilymphocyte Serum; D007166:Immunosuppressive Agents