Analysis of Plasma Products for Cellular Contaminants: Comparing Standard Preparation Methods

BACKGROUND

Recent reports suggest that component plasma products contain significant quantities of cellular contamination. We hypothesized that leukoreduction of whole blood before preparation of derived plasma is an effective method to prevent cellular contamination of stored plasma.

STUDY DESIGN

Samples of never-frozen liquid plasma prepared by standard methods (n = 25) were obtained from 3 regional blood centers that supply 3 major trauma centers. Samples were analyzed for leukocyte and platelet contamination by flow cytometry. To determine if leukoreduction of whole blood before centrifugation and expression of plasma prevents cellular contamination of liquid plasma, 1 site generated 6 additional units of liquid plasma from leukoreduced whole blood, which were then compared with units of liquid plasma derived by standard processing.

RESULTS

Across all centers, each unit of never-frozen liquid plasma contained a mean of 12.8 ± 3.0 million leukocytes and a mean of 4.6 ± 2 billion platelets. Introduction of whole blood leukoreduction (LR) before centrifugation and plasma extraction essentially eliminated all contaminating leukocytes (Non-LR: 12.3 ± 2.9 million vs LR: 0.05 ± 0.05 million leukocytes) and platelets (Non-LR: 4.2 ± 0.3 billion platelets vs LR: 0.00 ± 0.00 billion platelets).

CONCLUSIONS

Despite widespread belief that stored plasma is functionally acellular, testing of liquid plasma from 3 regional blood banks revealed a significant amount of previously unrecognized cellular contamination. Introduction of a leukoreduction step before whole blood centrifugation essentially eliminated detectable leukocyte and platelet contaminants from plasma. Therefore, our study highlights a straightforward and cost-effective method to eliminate cellular contamination of stored plasma.

Plasma Transfusion Products and Contamination with Cellular and Associated Pro-Inflammatory Debris

BACKGROUND

Stored plasma products are widely regarded as being functionally acellular, obviating the need for leukoreduction. We tested the hypothesis that donor plasma is contaminated by leukocytes and platelets, which, after frozen storage, would release cellular debris in quantities sufficient to elicit significant pro-inflammatory responses.

STUDY DESIGN

Samples of never-frozen liquid plasma from 2 regional Level I trauma centers were analyzed for leukocyte and platelet contamination. To determine if the cellular contamination and associated debris found in liquid plasma were at levels sufficient to evoke an innate immune response, known quantities of leukocytes were subjected to a freeze-thaw cycle, added to whole blood, and the magnitude of the inflammatory response was determined by induction of interleukin-6.

RESULTS

Units of never-frozen plasma from 2 regional Level I trauma centers located in Alabama and Louisiana contained significant amounts of leukocyte contamination (Louisiana, n = 22; 17.3 ± 4.5 million vs Alabama, n = 22; 11.3 ± 2.2 million) and platelet contamination (Louisiana, n = 21; 0.86 ± 0.20 billion vs Alabama, n = 22; 1.0 ± 0.3 billion). Cellular debris from as few as 1 million leukocytes induced significant increases in interleukin-6 levels (R² = 0.74; p < 0.0001).

CONCLUSIONS

Stored plasma units from trauma center blood banks were highly contaminated with leukocytes and platelets, at levels more than 15-fold higher than sufficient to elicit ex vivo inflammatory responses. In light of paradigm shifts toward the use of more empiric plasma for treatment of hypovolemia, this study suggests that new manufacturing and quality-control processes are needed to eliminate previously unrecognized cellular contamination present in stored plasma products.