Preparation of NPR and PR platelets. In each trial (n = 3), platelets from multiple donors (n = 6) were pooled and then split into 2 identical units. Using the INTERCEPT blood system, PR platelets were treated with amotosalen, which, under UVA illumination, resulted in nucleic acid modification to prevent pathogen replication. NPR platelets were then compared with PR platelets from the same pooled donors in subsequent experiments. This procedure was conducted for each of the 3 trials used. Other than treatment with pathogen reduction, the NPR and PR platelets underwent identical preparation, storage, and experimental procedures.