title: Anomalous changes in forward scatter of lymphocytes with loosely packed membranes.
abstract: BACKGROUND
  Forward scatter (FSC) is generally associated with cell size and has been suggested as a way to differentiate apoptotic from viable cells. Among spleen cells cultured for 48 h, a population of cells (population B) was found to have decreased forward and increased side scatter relative to freshly purified cells (population A). Interestingly, population B was not present early in analysis; this report explores the change in FSC of population B.
  
  
  METHODS
  Using a Coulter (Hialeah, FL) Epics Elite ESP flow cytometer, changes in forward scatter and lipid packing of spleen cells were measured.
  
  
  RESULTS
  Over time, the FSC of unfixed cells in population B increased from that of the debris field, to reach a stable value by 30 sec (population A's FSC remained constant). When fixed, populations A and B exhibited constant FSC. Population B cells displayed altered lipid packing as reported by MC540, and the FSC changes were mimicked by Nonidet P-40 treatment of freshly purified spleen cells.
  
  
  CONCLUSIONS
  Data emphasize the importance of delaying measurements on unfixed cells until FSC readings have stabilized, and suggest that flow cytometry may be a useful tool in studying lipid packing.
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana. jscherer@iupui.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Scherer
authors.forename: W
authors.initials: W
authors.lastname: Stillwell
authors.forename: L J
authors.initials: LJ
authors.lastname: Jenski
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D008214:Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009336:Necrosis; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000633:toxicity; D011419:Propidium / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000187:drug effects
chemical_list: D017304:Annexin A5; D008563:Membrane Lipids; D011419:Propidium; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40