EFFECT OF HLA-DR ANTIBODY CONCENTRATION ON ESTIMATION OF THE NUMBER OF CD14⁺HLA-DR^{LOW /–}-CELLS IN THE BLOOD OF PATIENTS WITH B-CELL chronic lymphocytic leukemia

. Immunoregulatory functions of myeloid-derived suppressor cells have been extensively studied over the recent decades. Additionally, myeloid-derived suppressor cells have been investigated as a prognostic factor. Objective. To optimize the measurement of monocytic myeloid-derived suppressor cells in the peripheral blood of patients with B-cell chronic lymphocytic leukemia. Materials and methods. The number of myeloid-derived suppressor cells with CD14 + HLA-DR low/– -phenotype was determined in the peripheral blood of patients with B-cell chronic lymphocytic leukemia and healthy donors by flow cytometry. The measurement was carried out at two points, which differed in the concentration of anti-HLA-DR antibodies − 15 and 4 μl. Results. The median amount of myeloid-derived suppressor cells in the peripheral blood of B-cell chronic lymphocytic leukemia patients with 15 μl of anti-HLA-DR antibody was 1.9 %, and with 4 μl of antibody concentration – 7 %. Healthy donors had that median of 0.15 % with 15 μl of antibody and 0.3 % with 4 μl concentration. Conclusion. The number of CD14 + HLA-DR low/– -cells in the blood of patients with B-cell chronic lymphocytic leukemia is sensitive to the concentration of the HLA-DR antibody. Compliance with patient rights and principles of bioethics. The study protocol No 3 of 13.02.2020 was approved by the biomedical ethics committee of Research Institute of Experimental Diagnostics and Therapy of Tumors N.N. Blokhin National Medical Research Center of Oncology of the Ministry of Health of the Russian Federation. All patients gave written informed consent to participate in the study.