Inactivation of pathogens in single units of therapeutic fresh plasma by irradiation with ultraviolet light.

BACKGROUND Ultraviolet (UV) light, especially UVC, is germicidal but its ability to penetrate layers of protein containing solutions is poor. This hampers its use to inactivate pathogens in therapeutic fresh plasma (FP). STUDY DESIGN AND METHODS FP units were spiked with lipid-enveloped or nonenveloped viruses. Others were used without spiking. The units were transferred into UV-transparent bags and irradiated with UVB or UVC light from both sides. The bags either were clamped between quartz plates or remained loose. In addition they were agitated at different speeds. Before and after irradiation virus titers or plasma variables were measured. RESULTS Virus inactivation by UV irradiation was marginal when the FP units were not agitated or when the irradiation bags were fixed between quartz plates. It was strongly enhanced when they remained unfixed and were intensively agitated during treatment. At 100 rpm and UVC doses of approximately 1 J/cm(2), with the exception of human immunodeficiency virus Type 1, all viruses used were effectively inactivated. UVB up to 2.5 J/cm(2) was less effective. At 1 J/cm(2) UVC or 2.5 J/cm(2) UVB the activities of the clotting factors tested in general were reduced by approximately 10% to 20% compared to untreated plasma. More sensitive was clotting factor XI whose activity was lowered by approximately 23 and 29%, respectively. No further reductions were determined after storage of UVC-treated FP for 3 months at 30 degrees C or less. CONCLUSIONS Pathogen inactivation of FP by UV light becomes effective when the unfixed irradiation bags are strongly agitated. The decrease in some clotting factor activities could be acceptable.