Immunophenotyping analysis of immune cells in the peripheral blood of a patient treated with fingolimod and corticosteroids for CNS GVHD. (A) Total lymphocyte counts, lymphocyte subsets absolute counts and changes in subset proportions of B and T cells were determined by flow cytometry. Fingolimod and corticosteroids were associated with lymphopenia and decreased B-cell, T-cell, and natural killer cell absolute counts. Treatment with fingolimod and corticosteroids was followed by an increase in the proportion of naive B cells (B), CD4⁺ (C), and CD8⁺ (D) effector memory T cells in the peripheral blood. T0, time of treatment initiation with fingolimod and corticosteroids to treat the second episode of CNS GVHD. Pretreatment samples were drawn at the time of diagnosis of the second episode of CNS GVHD, 17 months after allo-HCT.