found that the number of Wilms’ tumor gene (WT1) peptide-specific cytotoxic CD8+ T lymphocytes and the number of interferon (IFN)-γ-producing mononuclear cells (MNC) stimulated by WT1 in peripheral blood of 5 patients with PNH were significantly increased compared with 8 normal controls. Here, WT1 is linked to paroxysmal nocturnal hemoglobinuria.