Real-time measurement of platelet shape change by light scattering under riboflavin and ultraviolet light treatment

BACKGROUNDThe adoption of pathogen reduction technologies (PRTs) is considered for the implementation of safer platelet (PLT) transfusion. However, the effects of PRT treatment including irradiation with ultraviolet (UV) light on PLT shape have not yet been fully clarified. STUDY DESIGN AND METHODSLeukoreduced PLT concentrates (PCs) were treated with riboflavin and UV light (Mirasol PRT, TerumoBCT). PLT shape and adenosine diphosphate (ADP)-induced shape change were evaluated by a light scattering method where the amplitude of the scattered signal intensity was measured as the indicator of the proportion of discoid PLTs. Using a modified fluorometer, the real-time effects of different wavelengths of UV light on PLT shape were examined over the range of 300 to 360 nm at the same dose. RESULTSThe proportion of discoid PLTs in the Mirasol PRT-treated PCs decreased immediately after treatment. The difference in the proportion between PRT-treated and untreated PLTs became larger with storage. Although this modification correlated significantly with the pH decrease and P-selectin expression, the Mirasol PRT-treated PLTs retained sufficient ability to undergo an ADP-induced shape change. In the study using the modified fluorometer, the proportion of discoid PLTs significantly decreased with the wavelength (<320 nm) of irradiated UV light. CONCLUSIONMirasol PRT treatment of PCs decreases the proportion of discoid PLTs, which seemed to be caused by the irradiation with UV light of short wavelengths (<320 nm), not that of long wavelengths (320 nm) in the Mirasol PRT system. Modification of UV light wavelength may improve the quality of PRT-treated PCs.