IFN-γ staining of peripheral blood lymphocytes of responding and nonresponding patients with mAA. Lymphocytes from 11 previously untreated patients with mAA were surface stained with CD4-tricolor (phycoerythrin-cyanine 5) and CD8-PE and intracellularly stained with IFN-γ-FITC. Patients with mAA received daclizumab therapy and were designated as responders or nonresponders based on improvement of bone marrow function by 3 months following treatment. The figure shows the ratio of MCF_sample/MCF_isotype of staining of peripheral blood lymphocytes. Values more than 2 SD above the mean of normal were said to be positive for IFN-γ.¹⁷  MCF indicates mean channel fluorescence.