When comparing T-cell skewing based on IGHV and sex we observed a significantly higher frequency of EM CD4+ T-cells in female vs. male mice with dominant IGHV1 CLL clones (median: IGHV1 female: 94.8%; IQR: 93.3–95.6%; IGHV1 males: 88.8%; IQR: 77.6–89.4%; p = 0.036), while levels of naïve CD4+ T-cells were significantly lower (median: IGHV1 female: 0.7%; IQR: 0.6–1.9%; IGHV1 males: 4.5%; IQR: 3.6–14%; p = 0.036; Supp. Here, CD4 is linked to B-cell chronic lymphocytic leukemia.