title: Cytotoxicity of normal and activated rat monocytes analyzed by flow cytometry.
abstract: BACKGROUND
  The cytotoxic potential of activated monocytes might play an important role during severe systemic immune reactions and thus needs further elucidation. As established cytotoxicity tests are not suitable for this purpose, we developed a flow cytometry-based method.
  
  
  METHODS
  During acute renal allograft rejection in the rat, monocytes were harvested by vascular perfusion and then purified by Percoll density gradient centrifugation and subsequent immunomagnetic negative selection. For comparison, natural killer (NK) cells were similarly isolated from spleen homogenates. Cytotoxicity was determined by flow cytometry using the fluorescein isothiocyanate-labeled NK-sensitive lymphoma Yac-1 as target. Necrotic cells were identified by propidium iodide, and apoptotic cells were identified by MC 540. Cytotoxicity was determined by the calculation of a cytotoxicity coefficient, zeta. The zeta coefficient describes the interrelation between the reciprocal proportion of target cells in a sample and the specific cytotoxicity, simultaneously allowing estimation of the contribution of contaminating NK cells.
  
  
  RESULTS
  The method showed a substantial cytotoxicity of activated monocytes and indicated different or additional cytotoxic mechanisms compared with NK cells. Our assay permitted a detailed study of effector and target cells and took cytotoxicity of contaminating cells into account.
  
  
  CONCLUSIONS
  The method is nonradioactive, easy to perform, and thus helpful in investigating the role of monocytes in several diseases.
authors: Institute of Anatomy and Cell Biology, Philipps-University, Marburg, Germany. stehling@mailer.uni-marburg.de
authors: Oliver
authors: O
authors: Stehling
authors: Veronika
authors: V
authors: Grau
authors: Birte
authors: B
authors: Steiniger
mesh_terms: D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D002470:Cell Survival; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods*; D003602:Cytotoxicity, Immunologic; D005434:Flow Cytometry / Q000379:methods*; D006084:Graft Rejection / Q000276:immunology; D016030:Kidney Transplantation / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology / Q000473:pathology; D008297:Male; D051379:Mice; D009000:Monocytes / Q000276:immunology* / Q000473:pathology; D016260:Monocytes, Activated Killer; D009336:Necrosis; D051381:Rats; D011917:Rats, Inbred Lew; D013047:Specific Pathogen-Free Organisms