Evaluation of the effects of different interleukin combinations on proliferation and cytotoxicity of natural killer cells

Background. One of the approaches to expand natural killer (NK) and NKT cells for subsequent CAR (chimeric antigen receptor) therapy is cultivation in the presence of certain cytokines and/or feeder cells.Aim. To evaluate the effect of combinations of interleukin (IL): IL-2 + IL-15, IL-2 + IL-15 + IL-21 or IL-2 alone on NK and NKT cells during long-term cultivation in the presence of autologous feeder cells, which were non-irradiated T lymphocytes activated by monoclonal antibodies (mAbs).Materials and methods. Peripheral blood and leukocyte-platelet concentrate were used as a source of peripheral blood mononuclear cell. After peripheral blood mononuclear cell isolation, the lymphocyte culture was activated using adsorbed mAbs to CD3 and CD28 receptors. Then, activated lymphocytes were cultured in the presence of IL-2 + IL-15, IL-2 + IL-15 + IL-21, or IL-2 alone, periodically assessing the increase in the total number of cells, expression of surface markers, and cytotoxic activity.Results. Using the combination of IL-2 + IL-15 + IL-21, the greatest increase in cells and maximum cytotoxicity were observed; the proportion of NKT cells (CD3+CD56+) by the end of the cultivation was also the highest compared to other cultivation modes and amounted to 59 %. In the presence of a combination of IL-2 and IL-15, lower cytotoxicity of the cultured lymphocytes was determined compared to other experimental options, which may be due to exhaustion of the cell population. Based on the literature data, the addition of IL-21 to the culture medium probably neutralizes this negative effect of IL-15.Conclusion. Based on the dynamics of proliferation, receptor expression and cytotoxicity of cultured lymphocytes, it can be concluded that the cytokine combination consisting of IL-2, IL-15 and IL-21 is most effective for enriching the NKT cell population upon stimulation with mAb and in the presence of autologous activated T lymphocytes. For the most effective generation of the NK cell population, it is necessary to use other feeder cells, probably of tumor origin, or other expansion protocols.