Interleukin-4-induced natural killer cell antitumor activity in metastatic melanoma patients.

NK cells are important effectors of innate immunity that mount the first line of defense toward tumor growth. Interleukin-4 (IL-4) has recently been shown to regulate NK cell function, although its role in the regulation of NK cell function in cancer patients has not been clarified. The aim of this study was to investigate the effect of IL-4 on the function and the receptor characteristics of CD16-defined NK cells and their cytotoxic CD16bright and regulatory CD16dim subsets. Peripheral blood lymphocytes obtained from 36 metastatic melanoma (MM) patients treated for 18 h with 10 ng/mL IL-4 were evaluated for NK cell cytotoxicity using the radioactive 51chromium release assay. Expression of the activating receptors NKG2D and CD161, as well as the inhibitory receptors CD158a and CD158b, was analyzed on CD3-CD16+ NK cells and their subsets by flow cytometry. IL-4 induced significant in vitro enhancement of NK cell activity, as well as increased expression of the CD107a degranulation marker, by CD3-CD16dim NK cells. NKG2D expression was also increased on CD3-CD16+ cells by IL-4 with no alteration of the expression of CD161 and inhibitory KIR receptors. Although in vitro treatment with IL-4 increased both the expression of NKG2D and the cytotoxicity of NK cells, it had no detectable effect on the transcription of the TGF-ß gene in NK cells of MM patients. The IL-4-induced NK cell cytotoxicity and increased activating NKG2D receptor expression may indicate an important antitumor effect of IL-4 with a potential application for immunotherapy of MM patients.

The role of cytokines in the regulation of NK cells in the tumor environment.

Natural killer (NK) cells are innate lymphoid cells that are important effectors in the first line of defense toward transformed cells. This is mediated both by direct cytotoxic mechanisms and by production of immunoregulatory cytokines. Recent evidence has shown that NK cells also display memory, similar to the cells of the adaptive immune system. Cytokines are pivotal for the maturation, activation and survival of NK cells. Interleukins (IL)-2, IL-12, IL-15, IL-18, IL-21 and type I interferons positively regulate NK cell function, either independently or in cooperation, whereas other cytokines, such as IL-23 and IL-27, may enhance or suppress NK cell function depending on the context. In the tumor microenvironment, TGFß, IL-10 and IL-6 suppress NK cell activity not only directly, but also indirectly, by affecting immunosuppressive cells and by antagonizing the effect of stimulatory cytokines, thereby dampening the antitumor response of NK cells and promoting subsequent tumor evasion and progression. Increased understanding of the NK cell response to cytokines has provided a better understanding of their impaired function in tumors which may aid in the development of novel immunotherapeutic strategies to enhance NK cell responses in cancer patients.

Attenuated in vitro effects of IFN-α, IL-2 and IL-12 on functional and receptor characteristics of peripheral blood lymphocytes in metastatic melanoma patients.

Considering tumor-induced suppression of lymphocytes the aim of this study was to investigate in vitro effects of IFN-α, IL-2, IL-12 and IL-18 as immunomodulating agents on the functional and receptor characteristics of peripheral blood lymphocytes (PBL) in metastatic melanoma (MM) patients compared to healthy controls (HC). In HC IFN-α, IL-2 and IL-12 enhanced mRNA level of perforin by inducing pSTAT-1 and pSTAT-5 signaling molecules. Additionally, the expression of NKG2D activating receptor and its DAP10 signaling molecule was upregulated by IL-2. Contrary to this, in MM patients only IL-2 by upregulating pSTAT-5 increased perforin-mediated cytotoxicity of lymphocytes. Furthermore, there was significantly negative correlation between the percentage of CD4+CD25bright+CD27+ regulatory T (Treg) cells and NK cell cytotoxicity, as well as the expression of NKG2D receptor on PBL in HC and MM patients. Therefore, the absence of IL-2 effect on the increase of NKG2D/DAP10 level in MM patients could be the consequence of the increased percentage of immunosuppressive CD4+CD25bright+CD27+ cells after this cytokine treatment in patients. However, in MM IL-12 significantly decreases the percentage of these inhibitory cells. Although IL-2 as a single agent has numerous side effects, it remains the important cytokine for PBL activation in melanoma immunotherapy. Additionally, the removal of Treg cells from patient PBL by IL-12 before in vitro stimulation with IL-2, may lead to the generation of more potent cytotoxic lymphocytes against tumor cells. Therefore, lymphocyte based therapy for MM patients should integrate not only the choice of appropriate immunostimulatory cytokine, but also the removal of inhibitory cells from tumor microenvironment.

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.

In-vitro activation of natural killer cells from regional lymph nodes of melanoma patients with interleukin-2 and interleukin-15.

Regional lymph nodes (LNs) represent the first barrier in lymphogenic tumor dissemination in melanoma. Natural killer (NK) cells, the effector cell subpopulation of the innate immune system, are in the first line of antitumor immune defense. Therefore, the aim of this study was to investigate the effect of interleukin (IL)-2 and IL-15, two cytokines with similar immune-enhancing effects, on antitumor cytotoxic function and immunophenotype of NK cells from regional LNs of melanoma patients. Mononuclear cells purified from regional LNs of 50 melanoma patients in clinical stage II-IV were treated in vitro for 72 h and 7 days with 200 IU/ml rhIL-2 and 25 ng/ml IL-15 at 37°C in 5% CO2. Both cytokines significantly augmented NK cell cytotoxic activity, transcription of the cytotoxic molecule perforin, and the level of functionally mature perforin in both nonmetastatic and metastatic regional LNs. IL-2 treatment increased the percentage of CD3CD56 NK cells by increasing the CD56 NK cell subset in both nonmetastatic and metastatic LNs, whereas IL-15 treatment did not affect the percentage of NK cells and their subsets. Both cytokines increased on NK cells from nonmetastatic and metastatic LNs the expression of CD69 early activation antigen, the NKG2D activating receptor, as well as CD16 and inhibitory killer-cell immunoglobulin-like receptor CD158b, both inherent to the mature and the cytotoxic NK cell phenotype. In conclusion, our data may indicate the therapeutic potential of the NK cell population from regional LNs either as immunotherapeutic targets or as adoptively transferred after activation with IL-2 or IL-15.

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.