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17-06-2012 | Immunology | Article

Pathogen inactivation technique increases bad reactions to plasma products


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MedWire News: Methylene blue-treated fresh frozen plasma (MB-FFP) may pose an increased risk for allergic reactions to patients undergoing blood transfusion, French researchers report.

Following the introduction of MB-FFP in France in the second half of 2008, there was an abnormally high number of allergic reactions reported to the French Health Products Agency (Agence française de sécurité sanitaire des produits de santé).

This prompted Paul Michel Mertes (Centre Hospitalier Universitaire de Nancy) and colleagues to compare the rates for severe (grade 2 "severe life-threatening" and grade 3 "resulting in death") allergic reactions to the different FFP products reported in France between 2005 and 2009.

They found that the frequency of severe reactions to MB-FFP was 1 in 7751, which was significantly higher than the rate for reactions to solvent/detergent-treated FFP (S/D-FFP), at 1 in 25,351, and to standard quarantined FFP (Q-FFP), at 1 in 19,269. The difference between the latter two products was not statistically significant.

The team then conducted a more detailed prospective investigation of 34 patients who developed reactions to FFP-MB. Of these, 31 patients had a favorable outcome, one died because of the allergic reaction, and the remaining two died of causes unrelated to the transfusion.

Serum tryptase concentrations were increased in 19 (75%) of 25 cases in which it was measured. Plasma histamine was increased in 12 (66%) of 18 cases, and skin test results were positive to MB in three (18%) of 17 cases.

In three cases, an allergen unrelated to transfusion (latex, protamine, and propofol) was indicated, while a history of hypersensitivity reaction to a labile blood product (platelet concentrate, FFP, or red blood cells) was reported in four cases. Hypersensitivity to MB was ruled out in nine cases due to recent previous or subsequent uneventful exposure.

Writing in the Journal of Allergy and Clinical Immunology, Mertes and co-authors explain that MB kills viral pathogens in FFP by destroying viral nucleic acid through the production of oxygen radicals.

They say that their findings "confirm that in some cases sensitization to MB could be responsible for the allergic reactions observed.

"However, in a larger proportion of cases, the responsibility of MB was ruled out. This supports the hypothesis of an increased allergic risk related to the pathogen inactivation process itself."

The team concludes: "Although the mechanism of this increased risk of allergic reaction remains to be elucidated, our results are a strong incentive for a thorough reevaluation of the benefit-to-risk ratio of pathogen reduction using MB."

By Laura Cowen

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