PRDM1 and influenza: Purified CD4+ T cells from medLNs of influenza-infected WT (Prdm1fl/fl) and Prdm1-CKO (Prdm1fl/flCD4cre) mice were treated with IL-2 for 24 hours after ex vivo influenza-specific peptide (NP311–325) stimulation and subjected to RNA sequencing (RNA-seq) analysis (Fig. 3A).