When comparing CLL and HC groups, we observed statistically similar levels of Ki67 and IL-4 both in BTLA-positive and BTLA-negative T cell subsets, except for Ki67 MFI, detected in patients’ BTLA-positive T cells, which was significantly increased compared to that seen in the corresponding HC population (p = 0.0008) (Table 3, Figure 4). Here, IL4 is linked to B-cell chronic lymphocytic leukemia.