We evaluated the expression of the exhaustion markers PDCD1 and LAG3 on T cells of spleen, lymph nodes and peripheral blood of sick TCL1tg mice with established CLL (the mean percentage of CD19+ CD5+ malignant B cells in the peripheral blood was 60·0% ± 33·3%). This evidence concerns the gene PDCD1 and B-cell chronic lymphocytic leukemia.