title: Description and investigation of white particulate matter in additive solution-1 red blood cell units.
abstract: BACKGROUND
  In January 2003, "white particulate matter" (WPM) was transiently observed in red blood cell (RBC) units collected predominately in the southeastern US. In this report, these events, their chronology, pertinent observations and investigations, and summaries and conclusions associated with WPM during the 2-week observation period are described.
  On January 27, 2003, WPM was first identified in RBCs; by January 31, 2003, 110 RBC units containing WPM had been identified. Elective surgeries were postponed. Approximately 400 RBC units containing WPM were inspected in the blood center and characterized into four types: I, II, III, and IV. A variety of preparations of aspirated WPM were made, including light and electron microscopic sections.
  
  
  CONCLUSIONS
  The rate of WPM-containing units was 1.67 percent (1 in 60 units), whereas the background incidence was less than 0.25 percent. Investigations revealed that WPM was composed of activated and nonactivated platelets (PLTs); no toxins, infectious agents, or agents of bioterrorism were identified. WPM correlated with certain variables studied, including PLT-rich components that had been centrifuged with a "hard spin" before leukoreduction and manufactured in one vendor's collection sets. Because the increased rate of appearance of WPM was a transient phenomenon, it is not clear whether this is a newly noticed or a new and different phenomenon from "aggregates" observed in the past.
authors.affiliation: Transfusion Medicine Program, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA. chillye@emory.edu
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Hillyer
authors.forename: John D
authors.initials: JD
authors.lastname: Roback
authors.forename: Krista L
authors.initials: KL
authors.lastname: Hillyer
authors.forename: Cassandra D
authors.initials: CD
authors.lastname: Josephson
authors.forename: Peter L
authors.initials: PL
authors.lastname: Page
mesh_terms: D001800:Blood Specimen Collection; D002449:Cell Aggregation; D017707:Erythrocyte Transfusion; D006801:Humans