IFNG and B-cell chronic lymphocytic leukemia: By taking advantage of the TCL1 CLL mouse model [72], the authors show that PD-1high T cells from leukemic mice have defects in IFN-γ and Granzyme B expression compared to aging normal mice, but they do not completely lose their cytotoxic capacity, although their ability to form immune synapses is significantly impaired compared with PD-1low cells.