title: White particulate matter found in blood collection bags consist of platelets and leukocytes.
abstract: BACKGROUND
  In late January 2003, some blood centers and hospitals throughout the US voluntarily sus-pended the use of some RBC and plasma units for trans-fusion due to the presence of unknown white particulate matter (WPM) in these units. To better understand the WPM phenomena, a number of technologies were used to establish the nature of the particulates observed in Terumo Collection sets.
  
  
  METHODS
  All AS-5 nonleuko-reduced RBCs and plasma units were visually inspected for WPM by placing the bags on a flat counter, undisturbed, for approximately 10 minutes and then perform-ing a visual examination for particles. Particles were isolated and placed on microscope slides or in plastic tubes for further analysis. Electron microscopy, bright field microscopy, differential interference contrast microscopy, infrared spectroscopy, and flow cytometry procedures were performed to establish the nature of the particulate matter. In addition, leukoreduction filters and blood transfusion sets were used on RBCs units with WPM.
  
  
  RESULTS
  The particles were mostly composed of PLTs and WBCs, and fragments of these cells. All macroscopic WPM was removed from RBCs with leukoeduction and transfusion filters.
  
  
  CONCLUSIONS
  WPM originated from PLTs and WBCs. Foreign matter (e.g., plastic) was not observed in any of the units. Leukoreduction and transfusion filters can be used to remove macroscopic WPM.
authors.affiliation: Department of Blood Research, Department of Pathology, Walter Reed Army Institute of Research, Silver Spring, MD, USA. frank.rentas@na.amedd.army.mil
authors.forename: F J
authors.initials: FJ
authors.lastname: Rentas
authors.forename: V W
authors.initials: VW
authors.lastname: Macdonald
authors.forename: S W
authors.initials: SW
authors.lastname: Rothwell
authors.forename: S J
authors.initials: SJ
authors.lastname: McFaul
authors.forename: L V
authors.initials: LV
authors.lastname: Asher
authors.forename: A M
authors.initials: AM
authors.lastname: Kennedy
authors.forename: P J
authors.initials: PJ
authors.lastname: Hmel
authors.forename: C J
authors.initials: CJ
authors.lastname: Meledandri
authors.forename: J M
authors.initials: JM
authors.lastname: Salata
authors.forename: R W
authors.initials: RW
authors.lastname: Harman
authors.forename: T J
authors.initials: TJ
authors.lastname: Reid
mesh_terms: D001792:Blood Platelets; D001800:Blood Specimen Collection; D001803:Blood Transfusion; D002449:Cell Aggregation; D005374:Filtration; D005434:Flow Cytometry; D006801:Humans; D007962:Leukocytes; D008853:Microscopy; D013055:Spectrophotometry, Infrared