JAK1/JAK2 inhibition reduces neutrophils and MHC-II expression. C57BL/6 mice were treated twice daily with 30 mg/kg ruxolitinib starting on day −1 before TBI. On day 2 after TBI, mice were sacrificed and analyzed by flow cytometry. (A) Absolute numbers of neutrophils (CD45⁺CD11b⁺Ly6G⁺) in mLN and ileum. (B) Representative histogram of MHC-II expression on CD45⁺CD11b⁺Ly6G⁺ neutrophils in ileum after ruxolitinib or solvent control treatment. (C) Frequency of MHC-II⁺ (% of CD45⁺CD11b⁺Ly6G⁺) neutrophils in ileum and mLN after ruxolitinib or solvent control treatment. (D) Fold change of MFI for MHC-II on MHC-II⁺CD11b⁺Ly6G⁺ cells isolated from mLN or ileum. (E) Fold change in absolute MHC-II⁺CD45⁺CD11b⁺Ly6G⁺ numbers by ruxolitinib treatment normalized to solvent control. (F) Correlation of MHC-II⁺CD45⁺CD11b⁺Ly6G⁺ neutrophil numbers in mLN vs ileum after ruxolitinib or solvent control treatment.