title: Characterization of mononuclear cells remaining in the leukoreduction system chambers of apheresis instruments after routine platelet collection: a new source of viable human blood cells.
abstract: BACKGROUND
  The yield of white blood cells (WBCs) extracted from whole-blood leukoreduction filters can be affected by the storage conditions and delay before filtration. Platelets (PLTs) collected with apheresis instruments (Trima Accel, Gambro BCT) are leukoreduced during the procedure on a fluidized particle bed in a leukoreduction chamber (LRS chamber). In this report, the residual cell content of these LRS chambers was characterized to determine whether it would be a valuable source of viable human blood cells.
  
  
  METHODS
  The content of LRS chambers was eluted by gravity, and peripheral blood mononuclear cells (PBMNCs) were purified on a Ficoll-Paque gradient. Analyses were performed before and after freezing. Proportions of CD3+, CD14+, CD16+, CD19+, CD34+, and CD45+ cells were determined by flow cytometry. The frequency of T cells expressing CD4, CD8, and CD27 and of B cells expressing immunoglobulin G (IgG), IgM, and CD27 was also determined.
  
  
  RESULTS
  LRS chambers held approximately 10(9) CD45+ cells representing the normal proportions of CD3+, CD14+, CD16+, and CD19+ cell populations of PBMNCs. A small fraction of these CD45+ cells were CD34+CD38+ cells (0.3 +/- 0.2%). The viability of these cells, measured before and after freezing, was more than 95 percent.
  
  
  CONCLUSIONS
  The residual cell content of Trima Accel LRS chambers recovered after PLT collection is a good source of viable monocytes and lymphocytes. These PBMNCs, containing CD3+, CD14+, CD16+, CD19+, and CD34+ cells can be frozen to prepare cell banks, which opens new avenues for utilization in several physiologic studies or even in cellular therapy applications.
authors.affiliation: Héma-Québec, Research and Development, Québec, Quebec, Canada. sonia.neron@hema-quebec.qc.ca
authors.forename: Sonia
authors.initials: S
authors.lastname: Néron
authors.forename: Louis
authors.initials: L
authors.lastname: Thibault
authors.forename: Nathalie
authors.initials: N
authors.lastname: Dussault
authors.forename: Geneviève
authors.initials: G
authors.lastname: Côté
authors.forename: Eric
authors.initials: E
authors.lastname: Ducas
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pineault
authors.forename: Annie
authors.initials: A
authors.lastname: Roy
mesh_terms: D015703:Antigens, CD / Q000032:analysis*; D064987:Cell- and Tissue-Based Therapy; D015925:Cryopreservation; D006801:Humans; D047589:Leukocyte Reduction Procedures / Q000295:instrumentation; D008214:Lymphocytes / Q000166:cytology*; D009000:Monocytes / Q000166:cytology*; D010983:Plateletpheresis / Q000295:instrumentation
chemical_list: D015703:Antigens, CD