IL18R1 and influenza: To determine whether IL-18Rα expression was further increased in influenza-specific CD8 T cells compared to the bulk CD8 T cell population in hospitalized influenza-A patients, we performed tetramer-associated magnetic enrichment on a subset of HLA-A2+ patients (n = 10) to enrich for influenza-specific CD8 T cells recognizing the immunodominant A2/M158 epitope (Supplementary Fig. 2c).