Our results also indicate the high diagnostic value of selected miRNAs (e.g., miR-155-5p, miR-29a) and immunosuppressive markers (PD-1, PD-L1, CTLA-4) in differentiating patients with CLL and SID and in assessing EBV reactivation (Supplementary Materials Table S13, S14). Here, PDCD1 is linked to B-cell chronic lymphocytic leukemia.