In the analyzed group of patients with CLL, a significantly lower percentage of T lymphocytes (CD3+), including both CD4 + and CD8 + subpopulations, was observed compared to healthy volunteers (HV), with a simultaneous significant increase in the percentage of B lymphocytes CD19+ (p < 0.000 for all parameters). This evidence concerns the gene CD8A and B-cell chronic lymphocytic leukemia.