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Background and objectives Pathogen reduction of donor platelets with amotosalen/UVA has been shown to effectively inactivate pathogens and also contaminating white blood cells (WBCs). We wanted to determine whether WBC inactivation could also decrease alloimmune refractoriness to donor platelets. Materials and methods Platelets were prepared from a donor dog's whole blood, and the platelets were either transfused without modification [standard (STD) platelets] or treated with amotosalen/UVA under conditions modelling the amotosalen/UVA Blood System for human platelets (APR) using either 4 or 3 J/cm2 of UVA exposure. Platelets were transfused weekly from a single donor dog for 8 weeks or until the recipient dog became refractory to their donor's platelets. Antibody samples were drawn weekly and tested against the donor dog's platelets and WBCs (CD8 and B cells). Results Only 1/7 (14%) dogs that received STD platelets accepted 8 weeks of donor transfusions. Following APR 4 J/cm2 donor transfusions, 3/9 (33%) recipients accepted their donor's transfusions, but only one recipient remained antibody negative. Following APR 3 J/cm2 donor transfusions, the same dose as used for human platelet transfusions, 7/10 (70%) recipients accepted their donor's transfusions, but only two remained antibody negative. Conclusion As a very high percentage of recipient dogs (70%) accepted APR 3 J/cm2 donor transfusions, these data suggest that preventing alloimmune platelet refractoriness may be another benefit of pathogen reduction using amotosalen/UVA.

Background and Objectives Blood Centre logistics, staffing and donor scheduling may be optimized if pathogen inactivation (PI) of platelets can be delayed until Day 1, but bacteria may rapidly grow during this time. This study evaluates bacterial PI performed 24 and 30 h after collection. Materials and Methods PAS-3 platelet units were collected on the Amicus and subsequently inoculated (3–53 CFU/unit) with 1of 5 transfusion relevant bacterial species (n = 3/organism). Units were then stored for either 24 ± 0·3 or 30 ± 0·3 h at 20–24°C with agitation, subsequently treated with amotosalen and UVA, and stored for 7 days. Samples were taken before and after inactivation, on Days 2, 5 and 7 for BacT/ALERT testing, and on Days 5 and 7 for plate counts. Results All samples from units taken prior to inactivation either demonstrated positive plate culture counts, or, in untreated positive controls, were culture-positive during storage. All contaminated units treated with amotosalen and UVA 24 after inoculation were culture-negative on all days tested. With inactivation performed 30 h following inoculation, one of 15 units (1-of-3 replicates) was culture-positive with Klebsiella pneumonia (1 × 109 CFU/ml) by Day 5. Conclusion Photochemical treatment did not inactivate 1 of 15 units to sterility in apheresis platelets stored in PAS with a 30-h delay between contamination and treatment, but did inactivate 15 of 15 units with a 24-h delay.

Background and Objectives A photochemical treatment process (PCT) utilizing amotosalen and UVA light (INTERCEPT™ Blood System) has been developed for inactivation of viruses, bacteria, parasites and leucocytes that can contaminate blood components intended for transfusion. The objective of this study was to further characterize the safety profile of INTERCEPT-treated platelet components (PCT-PLT) administered across a broad patient population. Materials and Methods This open-label, observational haemovigilance programme of PCT-PLT transfusions was conducted in 21 centres in 11 countries. All transfusions were monitored for adverse events within 24 h post-transfusion and for serious adverse events (SAEs) up to 7 days post-transfusion. All adverse events were assessed for severity (Grade 0–4), and causal relationship to PCT-PLT transfusion. Results Over the course of 7 years in the study centres, 4067 patients received 19 175 PCT-PLT transfusions. Adverse events were infrequent, and most were of Grade 1 severity. On a per-transfusion basis, 123 (0·6%) were classified an acute transfusion reaction (ATR) defined as an adverse event related to the transfusion. Among these ATRs, the most common were chills (77, 0·4%) and urticaria (41, 0·2%). Fourteen SAEs were reported, of which 2 were attributed to platelet transfusion (