Treatment of platelet concentrates with ultraviolet C light for pathogen reduction increases cytokine accumulation

Per Sandgren, Gösta Berlin, Nahreen Tynngård

Pathogen reduction technologies use photoactive substances in combination with ultraviolet (UV) light to inactivate pathogens. A new method uses only UVC light for pathogen reduction. This study assesses the effects of UVC light treatment on cytokine release in platelet (PLT) concentrates (PCs). A PC with 35% plasma and 65% PLT additive solution (SSP+) was prepared from five buffy coats. Three such PCs were pooled and divided into 3 units. One unit was used as a nonirradiated control, the second was a gamma-irradiated control, and the third unit was treated with UVC light technology. Ten units of each type were investigated. Cytokine release was analyzed on Days 1, 5, and 7 of storage. Correlation between cytokines, PLT surface markers, and hemostatic properties was investigated. Swirling was well preserved and pH was above the reference limit of 6.4 during storage of PLTs in all groups. Cytokine levels increased during storage in all groups but to a larger degree in PCs treated with UVC light. Only weak correlation was found between cytokines and PLT surface markers (r < 0.5). However, several cytokines showed strong correlation (r > 0.6) with the PLTs' ability to promote clot retraction. UVC treatment resulted in increased release from PLT alpha granules as evident by a higher cytokine release compared to nonirradiated and gamma-irradiated PCs. The clinical relevance of these findings needs to be further evaluated.