Protein and metabolite correlates to kynurenine levels in the REDS RBC Omics recalled donor cohort. (A) For the 643 recalled donor units (storage day 10, 23, and 42), proteomics and metabolomics data were generated to identify omics correlates to kynurenine levels. (B) Results indicate an enrichment between kynurenine levels and complement and fibrinogen components during a depletion in the levels of RBC structural and functional proteins. (C) At the metabolic level, increases in kynurenine were accompanied by elevation of all intracellular amino acids, especially aromatic amino acids. (D) Pathway analysis of combined metabolomics and proteomics data indicates an enrichment in components involved in viral responses, complement, and coagulation. CFD, complement factor D; CFH, complement factor H; FGA, fibrogen alpha chain; FGB, fibrinogen beta chain; FGG, fibrogen gamma chain; HPX, hemopexin.