• Journal of Ginseng Research
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• v.13 no.2
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• pp.223-228
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• 1989

Natural killer (NK) cells are a heteroguneous subpopulation of lymphocytes that spontaneously exhibit cytotoxic activity against various virus-Infected and neoplastic target cells without prior exposure to a specific antigen. It was thought that NK calls play an important role in immunosurvrillanre against viral agents and tumors, and in prevention of metastasis. Recently, several reports have indicated evidence that ginseng extracts show a significant stimulatory effect on the humoral and cellular immune responses. This evidence gives support to the suggestion that the anticarcinogenic effect of ginseng may be due to the effect of ginseng on the immunological system. Treatment with total, diol, and triol saponin resulted in an increase in NK cytotoxic activity, but no enhancement of the lytic activity due to the natural killer cytotoxic factor (NKCF). Therefore, these results suggest that the augmentation of NK activity by ginseng saponin fractions may not be due to the activation of NKCF lytic activity.

• Korean Journal of Psychosomatic Medicine
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• v.3 no.1
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• pp.3-10
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• 1995

A comparison was made between the effect of subjective stress and that of objective stress on immune function in male medical college students. Interaction between perceived stress, psychopathology and natural killer-cell(NK) activity was assessed during an exam period, non-exam period, and vacation. No significant difference was found in NK activity among these three periods, but scores of perceived stress related to unusual happenings during an exam period and related to interpersonal relationship during vacation were found to have significantly positive correlation with NK activity, respectively. In psychopathology, only scores of anxiety during an exam period had significantly positive correlation with NK activity. These results suggest that immune function is more likely to be affected by subjective stress than objective stress and that subjective stress such as some perceived stress and subclinical level of anxiety may positively affect immune function.

• Korean Journal of Veterinary Research
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• v.32 no.2
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• pp.245-250
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• 1992

This study was performed to demonstrate the presence of large granular lymphocyte(LGL) in Sprague-Dawley(SD) rats and morphologically observe NK cell and also establish the method of isolation of natural killer cell in SD rats. By percoll discontinuous density gradients centrifugation, highly enriched LGL population were shown to fraction 2(border line between 44.2% and 50.8%). LGL were shown to bind selectively to YAC1 mouse lymphoma cell. This fraction expressed very high NK cell cytolysis. Therefore, we thought that LGL have NK activity in SD rats. The Morphology of rat LGL is very similar to that of human LGL. These cells have an eccentric kidney-shaped nucleus. Their most distinctive feature was their cytoplasmic azurophilic granules. Another distinguishing feature of rat LGL was their high cytoplasmic : nuclear ratio. It was concluded that LGL played a role part in mediating natural killer activity in this species.

• Journal of Haehwa Medicine
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• v.21 no.1
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• pp.87-96
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• 2012

Aim : Natural killer (NK) cells are cytotoxic lymphocytes that lyse certain tumor- and virus-infected cells without any prior stimulation or immunization. This article aims to review the significance of evaluating peripheral blood NK cells to predict anti-tumor immune function and prognosis in cancer patients. Methods : PubMed was used to create a database for this review. Search words of cancer, natural killer cell, prognosis were used to retrieve related articles. References of the collected articles were also reviewed. Results : Current evidence indicates that decreased or absent NK cell count or activity is mostly associated with the development or progression of cancer. In patients with various types of cancer, NK cell activity was mostly associated with the cancer prognosis and survival despite some conflicting results. Conclusion : The data shows the evaluation of anti-tumor immunity in cancer patients through natural killer cell measurement still remains a controversial matter. However, it is clear that the NK cell activity plays an important role in cancer and is associated with prevention of both early stage and metastatic cancer.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1991.06a
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• pp.20-20
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• 1991

악성종양의 발생과 진행에 면역 방어기능이 중요한 역할을 하리라는 가설은 모두가 공감하는 사실이다. 이중 T-lymphocyte와 Natural killer cell (이하 NK cell이라함)은 종양 면역학에 특히 중요한 임파구로 이런 임파구의 혈액분포양상은 면역방어기능을 짐작할 수 있는 간접적인 자료가 될 수 있다. 저자들은 치료전 두경부 악성종양환자에서 혈액을 채취하여 T-lymphocyte와NK cell의 분포양상을 검사하고, 방사선치료 환자에서는 NK cell activity를 측정하였기에 다음과 같은 결과를 보고하는 바이다. 1) 두경부 악성 종양 환자군에서 CD3+ cell은 감소하고 NK cell은 증가하며 CD4/CD8 비율은 변화가 없었다. 2) 병변이 진행되면서 CD3+ cell과 CD4+ cell은 감소하고 NK cell은 증가하였으며 CD4/CD8 비율의 변화는 없었다. 3) 방사선치료에 의해 CD3+ cell과 CD4+ cell, CD4/CD8 비율은 감소하였고, NK cell과CD8+cell은 증가하였다. 4) 방사선치료에 의한 CD4/CD8 비율의 감소와, CD8+ cell의 증가는 NK cell의 증가에 의한 것이라 추정되고, NK cell을 제외하면 CB4/CD8 비율의 변화는 없었다. 5) 방사선치료 환자에서 NK cell activity는 증가하였고, 이런 증가가 T-lymphocyte기능의 감소를 보상해 주고 있었다.

• Biomedical Science Letters
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• v.29 no.3
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• pp.178-183
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• 2023

Natural killer (NK) cells are innate cytotoxic lymphoid cells that actively prevent neoplastic development, growth, and metastatic dissemination in a process called cancer immunosurveillance. Regulation of the cytotoxic activity of NK cells relies on integrated interactions between inhibitory receptors and numerous activating receptors that act in tandem to eliminate tumor cells efficiently. Conventional chemotherapy is designed to produce an anti-proliferative or cytotoxic effect on early tumor cell division. Therapies designed to kill cancer cells and simultaneously maintain host anti-tumor immunity are attractive strategies for controlling tumor growth. Depending on the drug and dose used, several chemotherapeutic agents cause DNA damage and cancer cell death through apoptosis, immunogenic cell death, or other forms of non-killing (i.e., mitotic catastrophe, senescence, autophagy). Among stress-induced immunostimulatory proteins, changes in the expression levels of NK cell activating and inhibitory ligands and tumor cell death receptors play an important role in the detection and elimination by innate immune effectors including NK cells. Therefore, we will address how these cytotoxic lymphocytes sense and respond to high and low concentrations of drug-induced stress to the drug cisplatin, among the various types of drugs that contribute to their anticancer activity.

• Journal of Microbiology and Biotechnology
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• v.32 no.4
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• pp.397-404
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• 2022

Natural killer (NK) cell activity is more attenuated in hepatocellular carcinoma (HCC) patients than normal. Hypoxic-inducible factor (HIF)-1α is highly expressed in tumors to maintain their metabolism in a hypoxic environment. The expression of HIF-1α in cancers can lead to cell growth, proliferation, invasion/metastasis and immune escape. Although apigenin, a flavonoid, is known to have various biological activities, it has not been demonstrated in NK cell immune activity in HCC cells. In this study, NK-92 cells were directly cocultured with HCC SK-Hep1 cells for 24 h to evaluate NK cell activity in HCC cells or HCC cells expressing HIF-1α by apigenin. NK cell cytotoxicity to HCC cells expressing HIF-1α was significantly increased, and NK cell-activating receptors, NKG2D, NKp30 and NKp44 were highly expressed. The activating effect of apigenin on NK cells substantially induced apoptosis in HCC cells expressing HIF-1α through high expression of CD95L on the surface of NK-92 cells. Moreover, apigenin excellently inhibited the level of TGF-β1 in a coculture of NK cells and HCC cells. In conclusion, apigenin seems to be a good compound that increases NK cell cytotoxicity to HCC cells by controlling HIF-1α expression.

• Korean Journal of Pharmacognosy
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• v.29 no.4
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• pp.293-299
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• 1998

The effects of Buthus martensi Karsch (BMK) on natural killer (NK) cell activity in mouse spleen were studied. Water extracted solution of BMK was orally administrated to Balb/c mice for 2 weeks. Among splenic cells, T cell fractions were separated by Nylon wool column. Furthermore, NK cell purification was performed 4.5% percoll gradients methods. The cytotoxcity of NK cell to K562 cell was determined by lactic acid dehydrogenase and $[^3H]-thymidine $ incorporation methods. And the cytotoxicity of effector cell was most effectively induced in a ration of 50:1 (effector/target cell). As a result, cytotoxicity of NK cells was significantly increased compared with control group both in vivo and in vitro systems. The similar cytotoxic effect was shown in $[^3H]-thymidine $ incorporation methods. This suggests that when BMK is administrated to mice with malignant tumors, an increase in NK cell activity may occur and affect K562 tumor cells.

• Development and Reproduction
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• v.24 no.1
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• pp.53-62
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• 2020

Natural killer (NK) cells are innate lymphocytes that play an essential role in preventing cancer development by performing immune surveillance to eradicate abnormal cells. Since ex vivo expanded NK cells have cytotoxic activity against various cancers, including breast cancers, their clinical potential as immune-oncogenic therapeutics has been widely investigated. Here, we report that the pyrazole chemical XRP44X, an inhibitor of Ras/ERK activation of ELK3, stimulates NK-92MI cells to enhance cytotoxic activity against breast cancer cells. Under XRP44X stimulation, NK cells did not show notable apoptosis or impaired cell cycle progression. We demonstrated that XRP44X enhanced interferon gamma expression in NK-92MI cells. We also elucidated that potentiation of the cytotoxic activity of NK-92MI cells by XRP44X is induced by activation of the c-JUN N-terminal kinase (JNK) signaling pathway. Our data provide insight into the evaluation of XRP44X as an immune stimulant and that XRP44X is a potential candidate compound for the therapeutic development of NK cells.

• Korean Journal of Pharmacognosy
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• v.22 no.4
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• pp.233-239
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• 1991

Phellinus linteus was examined for its anticancer activity using an animal model. Water extract of Phellinus linteus was prepared from artificially cultivated mycelia. Neither toxicity nor abnormal changes of hematological parameters were observed in the rat given orally with high doses of drug extract for 15 days. ICR mice were transplanted with Sarcoma-180 tumor cells intraperitoneally and drug extract was daily given to the mice from 1 day after tumer transplantation for 3 weeks. Administration of drug extract significantly prolonged the survival duration of Sarcoma 180-transplanted mice. For the better understanding of the anticancer activity, we have examined the effect of the drug extract administration on various killer cell functions, such as natural killer(NK) cells, cytotoxic T-lymphocytes (CTL) and macrophages which have been known to be main effector cells in immune responses against tumors. The results from the 4 hr $^{51}Cr-release$ assay have shown that the drug extract augments mouse NK cell activity but neither CTL nor macrophages. It is possible, then, that the anticancer activity of the Phellinus linteus may be associated with augmentation of NK cell function in the cancerated hosts.