In F-MS patients, the mean frequency of IFN-γ-producing cells in CD56− T cells was increased both in relapse-free F-MS (27.1%) and relapsed F-MS (43.7%) patients compared with HS (9.7%) and nF-MS patients (8.7% in remission and 9.0% at relapse). The gene discussed is IFNG; the disease is myeloid sarcoma.