Human Peripheral Blood Mononuclear Cells-CLL

IL-27 Effects on Lymphocyte Population Distribution

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of malignant B cells and the gradual loss of immune function. T-cell exhaustion marker TIM-3 and its ligand galectin-9 (Gal-9) are negative regulators of antitumor immunity. Interleukin-27 (IL-27) is pleiotropic cytokine with immunomodulatory properties; however, its effects on TIM-3/Gal-9 expression in CLL have not been well characterized.

PBMCs from 20 treatment-naïve CLL patients were cultured with or without IL-27 (100 ng/mL, 72 h), and expression of multiple checkpoints was measured by flow cytometry. IL-27 induced significant changes in the proportion of circulating lymphocyte subsets. CD4⁺ T helper cells were the most significantly affected cell population with proportions decreasing from 26.71 ± 4.19% (median 23.59%) to 22.01 ± 3.23% (median 21.77%) following IL-27 stimulation. Although this difference was numerically small (~4.7 percentage points), this could still have biological significance as it affects the balance of T-cell subsets in CLL. Total CD3⁺ T cells also trended towards decreased proportions after IL-27 treatment with percentages going from 43.26 ± 5.94% (median 42.57%) to 36.85 ± 5.48% (median 40.18%). No other statistically significant differences were detected with CD8⁺ T cells or CD19⁺ B cells. Although further studies are needed to understand the functional consequences of IL-27 treatment in CLL, the data presented here suggest IL-27 preferentially affects the CD4⁺ T-cell compartment. Figure 1 depicts an example gating strategy used for flow cytometry. Figure 2 displays the results of flow cytometry after IL-27 treatment.