Moreover, Tregs of CLL patients exhibited increased expression of markers for activation and immunosuppression, such as cytotoxic T-lymphocyte associated protein 4 (CTLA-4), which was confirmed in Eμ-TCL1 mice [37] as well as the TCL1 AT mouse model [27, 32, 38–40]. This evidence concerns the gene CTLA4 and B-cell chronic lymphocytic leukemia.