Beneficial in-vitro effects of interleukin-2, interleukin-12, and their combination on functional and receptor characteristics of natural killer cells in metastatic melanoma patients with normal serum lactate dehydrogenase levels.

Considering tumor-mediated suppression of natural killer (NK) cells, the aim of this study was to investigate the in-vitro effects of interleukin (IL)-2 and IL-12, as immunostimulatory cytokines, on the functional and receptor characteristics of NK cells and their subsets in healthy control (HC) and metastatic melanoma (MM) patients. Peripheral blood mononuclear cells of 27 HC and 35 MM patients were stimulated in vitro with IL-2, IL-12, and their combination for functional and phenotypic analysis. IL-2, IL-12, and primarily their combination, significantly induced NK cell activity, CD107a degranulation marker, and perforin expression in NK cells and their subsets in HC and MM patients. Furthermore, the combination of IL-2 and IL-12 was significantly more efficient than IL-12 alone in the augmentation of NK cell cytotoxicity and CD107a expression. Also, IL-2 and IL-12 reciprocally upregulated each other's receptors, IL-2Rα and IL-12Rß1/ß2, on NK cells and their subsets in MM and HCs. In addition, the priming of NK cells with IL-2 before IL-12 treatment led to an increase in the expression of both IL-12 receptors. In contrast to IL-12, IL-2 increased activating NKG2D and DNAM-1, as well as inhibitory CD158a and CD158b KIRs. In addition, the cytokines investigated exerted a more potent effect on the increase in NK cell activity and the expression of various NK cell receptors in MM patients with normal lactate dehydrogenase (LDH) serum levels. Therefore, serum LDH could represent a predictor of response to cytokine immunotherapy in MM patients. The optimization of combined IL-2/IL-12 therapy is needed to enhance NK cell functions in MM patients stratified by their LDH levels.

Decreased expression of NKG2D, NKp46, DNAM-1 receptors, and intracellular perforin and STAT-1 effector molecules in NK cells and their dim and bright subsets in metastatic melanoma patients.

Although natural killer (NK) cells play an important antitumor role, melanoma cells may affect their effector functions. In this study, we analyzed the expression of various receptors and effector molecules in NK cells and their subsets in metastatic melanoma (MM) patients compared with healthy controls (HCs). In HC and MM patients, we analyzed NK cell activity using a chromium release assay and the expression of CD107a degranulation marker, activating NKG2D, NKp46, DNAM-1, and inhibitory CD158a and CD158b receptors, IL-12R beta 1, IL-12R beta 2, intracellular interferon (IFN)-γ, perforin, and STAT-1 in CD3-CD56+ NK cells, and cytotoxic CD3-CD56 and immunoregulatory CD3-CD56 subsets by flow cytometry. MM patients compared with HC not only had significantly decreased NK cell activity, lower expression of CD107a, and impaired IFN-γ production but also had decreased expression of activating NKG2D, NKp46, and DNAM-1 receptors, which was followed by lower expression of perforin, STAT-1, and both IL-12R subunits in NK cells. In MM patients only, there was a positive correlation between NKG2D expression and degranulation capacity, as well as IFN-γ production in NK cells. Analysis of the expression of various parameters of NK cell effector functions between MM patients with different localization of distant metastases showed that patients in the unfavorable M1c subclass had decreased expression of NKG2D and NKp46 on NK cells compared with patients in the M1a+b group. Downregulated NKG2D, NKp46, and DNAM-1 receptors associated with impaired NK cell effector function are important biomarkers of advanced disease with a poor prognosis in melanoma patients.