TNFSF13B and B-cell chronic lymphocytic leukemia: We demonstrated that CLL patients displayed significantly lower levels of serum BAFF compared to healthy controls (median, IQR: 0 pg/mL, 0–20.7 versus 28.3 pg/mL, 21.6–48.1; P ≤ 0.001) (Figure 3), while the majority of patients (30 out of 57 analyzed, 52.6%) exhibited undetectable levels using a hypersensitive BAFF detection kit.