Related Experiment Video
Updated: Aug 15, 2026
Controlled Microfluidic Environment for Dynamic Investigation of Red Blood Cell Aggregation
Published on: June 4, 2015
Description and investigation of white particulate matter in additive solution-1 red blood cell units
Christopher D Hillyer1, John D Roback, Krista L Hillyer
1Transfusion Medicine Program, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA. chillye@emory.edu
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.
Chronology And Investigations:
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.
Results And 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.
Insights
White particulate matter (WPM) in red blood cell units was investigated in early 2003. WPM consisted of platelets and was linked to specific collection methods, resolving as a transient issue.
Area of Science:
- Transfusion Medicine
- Hematology
- Blood Component Safety
Background:
- Transient observation of white particulate matter (WPM) in red blood cell (RBC) units occurred in January 2003, primarily in the southeastern US.
- This report details the chronology, investigations, and conclusions regarding WPM events during a two-week period.
Purpose of the Study:
- To investigate the nature and origin of white particulate matter (WPM) observed in red blood cell (RBC) units.
- To determine the incidence, characteristics, and potential causes of WPM during a specific observation period.
Main Methods:
- Identification and inspection of approximately 400 RBC units containing WPM.
- Characterization of WPM into four types (I-IV).
- Microscopic examination (light and electron) of WPM preparations.
Main Results:
- WPM was identified in 1.67% of RBC units, a significant increase from the background incidence (<0.25%).
- Investigations revealed WPM comprised activated and nonactivated platelets (PLTs).
- No toxins, infectious agents, or bioterrorism agents were identified as causes.
Conclusions:
- WPM formation correlated with specific variables, including centrifugation of PLT-rich components with a "hard spin" before leukoreduction and use of certain collection sets.
- The increased WPM rate was transient, raising questions about whether it represents a newly observed phenomenon or a variation of previously identified "aggregates."
- The findings underscore the importance of monitoring blood product quality and understanding factors influencing component integrity.
