Tissue detection of natural killer cells in laryngeal carcinoma

Natural Killer (NK) cells have gained much attention as potential cells in antitumor immune defense mechanisms. In a group of 31 patients with surgically treated squamous cell laryngeal carcinoma, NK cell presence was semiquantitatively assessed by means of immunohistochemistry. A panel of three monoclonal antibodies including anti-CD16, was applied on frozen tissue sections. High CD 16+ cell presence was more frequently detected in poorly differentiated carcinomas (in 6 out of 14 cases) by comparison to carcinomas of high to moderate degrees of differentiation (in 1 out of 16 cases, p=0.031). No other clinicopathological variable appeared to influence NK cell presence in the examined specimens. No relation between NK cell detection and relapse-free survival emerged. Poorly differentiated laryngeal cancer cells appear to trigger off a greater NK cell tissue response than well and moderately differentiated cancer cells; however, the potential prognostic impact of this observation remains to be established.     

Natural killer cells and natural killer T cells

NK cells are important in protecting against viral infections, and they may regulate the immune response. They are activated by hematopoietic blasts and pose a barrier to bone marrow transplantation. They are also abundant in the pregnant uterine decidua, although their role there is unknown. NK cells are normally inhibited from responding to host cells by inhibitory receptors that recognize self class I MHC antigens. There is evidence that NK cells may be important in the regulation of autoimmunity, but there is even stronger evidence that NKT cells regulate autoimmunity. The mechanisms by which these cells are activated and by which they regulate other cells are now being understood at the molecular level.     

Human natural killer cells

Natural killer (NK) cells were discovered more than 30 years ago. NK cells are large granular lymphocytes that belong to the innate immune system because unlike T or B lymphocytes of the adaptive or antigen-specific immune system, NK cells do not rearrange T-cell receptor or immunoglobulin genes from their germline configuration. During the past 2 decades there has been a substantial gain in our understanding of what and how NK-cells "see," lending important insights into their functions and purpose in normal immune surveillance. The most recent discoveries in NK-cell receptor biology have fueled translational research that has led to remarkable results in treating human malignancy.     

Alterations in natural killer cells and natural killer T cells during acute viral hepatitis E

The mechanism of liver damage in acute hepatitis E is poorly understood. In this study, we assessed the frequency and activation status of natural killer (NK) and natural killer T (NKT) cells and cytotoxic activity of NK cells in the peripheral blood mononuclear cells (PBMCs) obtained from patients with hepatitis E (n = 41) and healthy controls (n = 61). Flow cytometry was used to assess NK (CD3(-)/CD56(+)) and NKT cell (CD3(+)/CD56(+)) fractions (% of PBMCs) and activation status (CD69(+); % of NK, NKT cells). NK cell cytotoxicity was assessed using major histocompatibilities complex-deficient K562 cells as target cells. In 14 patients, the studies were repeated during the convalescence period. Patients had fewer median (range) NK cells [8.9% (2.4-47.0) vs 11.2% (2.6-35.4)] and NKT cells [8.7% (2.8-34.1) vs 13.6% (2.3-36.9)] than controls (P < 0.05 each). Activation markers were present on large proportion of NK cells [43.5% (11.2-58.6) vs 15.5% (3.0-55.8)] and NKT cells [41.5% (17.4-71.1) vs 12.8% (3.3-63.2); P < 0.05 each] from patients. NK cell cytotoxicity was similar in patients and controls. During convalescence, all the parameters normalized. In conclusion, reversible alterations in NK and NKT cell number and activation status during acute hepatitis E suggest a role of these cells in the pathogenesis of this disease.     

Cytokine-induced memory-like natural killer cells

The mammalian immune response to infection is mediated by 2 broad arms, the innate and adaptive immune systems. Innate immune cells are a first-line defense against pathogens and are thought to respond consistently to infection, regardless of previous exposure, i.e., they do not exhibit memory of prior activation. By contrast, adaptive immune cells display immunologic memory that has 2 basic characteristics, antigen specificity and an amplified response upon subsequent exposure. Whereas adaptive immune cells have rearranged receptor genes to recognize the universe of antigens, natural killer (NK) cells are innate immune lymphocytes with a limited repertoire of germ-line encoded receptors for target recognition. NK cells also produce cytokines such as IFN-gamma (IFN-γ) to protect the host during the innate response to infection. Herein, we show that cytokine-activated NK cells transferred into naïve hosts can be specifically detected 7–22 days later when they are phenotypically similar to naïve cells and are not constitutively producing IFN-γ. However, they produce significantly more IFN-γ when restimulated. This memory-like property is intrinsic to the NK cell. By contrast, memory-like NK cells do not express granzyme B protein and kill targets similarly to naïve NK cells. Thus, these experiments identify an ability of innate immune cells to retain an intrinsic memory of prior activation, a function until now attributed only to antigen-specific adaptive immune cells.     

Human and murine inhibitory natural killer cell receptors transfer from natural killer cells to target cells

Intercellular transfer of proteins across the immunological synapse is emerging as a common outcome of immune surveillance. We previously reported that target-cell MHC class I protein transfers onto natural killer (NK) cells expressing cognate killer Ig-like receptors (KIRs). We now show that, for both murine and human cells, target cells expressing inhibitory MHC class I ligands acquire cognate inhibitory NK receptors. Other cell-surface proteins, but not a cytoplasmic dye, also transferred from human NK cells to target cells across an inhibitory immunological synapse. The number of KIRs acquired from NK cells correlated with the level of expression of cognate MHC class I protein on target cells. Treatment with cytoskeletal inhibitors demonstrated that the target-cell cytoskeleton influences intercellular transfer of proteins in both directions. In contrast to constitutively expressed KIRs, a fraction of acquired KIRs could be removed by mild acid wash, demonstrating a difference between some of the acquired KIRs and constitutively expressed KIRs. An accumulation of phosphotyrosine at the location of the transferred KIRs implies a signaling capacity for NK cell proteins transferred to target cells. Thus, intercellular protein transfer between immune cells is bidirectional and could facilitate new aspects of immune cell communication.     

Liver injury due to sequential activation of natural killer cells and natural killer T cells by carrageenan

BACKGROUND/AIMS: Carrageenan is a high molecular weight polysaccharide and is widely used as a food additive for the solidification of plant oils and the thickening of many beverages. It is known that acute toxicity of carrageenan is possibly induced by the activation of phagocytic cells. We investigated other effects of carrageenan on lymphocytes in this study. METHODS: Carrageenan was intraperitoneally injected once into mice and phenotypic and functional characterizations were conducted in various immune organs. RESULTS: Natural killer (NK) cells were prominently activated in the liver, lungs, and spleen. A time-kinetic study showed sequential activation of NK and natural killer T (NKT) cells in the liver on days 3-10 after the injection. In parallel with the activation of NK and NKT cells in number, NK and NKT cytotoxicities were augmented. At this time, liver injury was induced, accompanied by massive hepatic necrosis and the elevation of transaminases. The in vivo elimination of NK cells reduced the liver injury induced by carrageenan. Direct binding of carrageenan onto NK cells was also demonstrated. Such a binding then induced a subsequent production of IFN gamma. Perforin molecules of NK cells were responsible for this liver injury. CONCLUSIONS: These results suggest that not only phagocytic cells but also primitive lymphocyte (mainly NK cells) subsets might be important targets for the acute toxicity of carrageenan.     

The role of natural killer cells in histoplasmosis

The natural killer (NK) cell has been suggested as an early defense mechanism against Histoplasma capsulatum. Homozygous bg/bg mice, heterozygous bg/+ mice, and bg/+ mice treated with anti-asialo GM1 (ASGM1) were used to assess this postulated role. NK cell assays demonstrated that ASGM1 was effective in reduction of NK cell activity in bg/+ mice to levels comparable to bg/bg mice. To test for possible cross reaction with other immune cells and ASGM1, we evaluated lymphocyte and macrophage function. These studies included lymphocyte transformation, delayed-type hypersensitivity (DTH), and macrophage candidacidal activity. We found no evidence of any effects from ASGM1. Mice were evaluated for survival and colony counts after intravenous (i.v.) H. capsulatum challenge. We again confirmed increased susceptibility of bg/bg mice to H. capsulatum, but found no significant differences between bg/+ mice and bg/+ mice treated with ASGM1. Therefore, we conclude that NK cells play no major role in nonspecific early host defenses against H. capsulatum.     

Leukemia of non-T lineage natural killer cells

An unusual case of an aggressive leukemia of natural killer (NK) cells occurred in a 65-year-old male. Clinical characteristics of this case included hepatosplenomegaly, ascites, marrow infiltrate with leukemic cells, and a WBC up to 82.8 X 10(9) before therapy. One year before his presentation he had been noted to have a WBC of 12.1 X 10(9) with 78% lymphocytes, and 6 months before had noted intermittent fever and weight loss. He and his brother had well documented hereditary cold urticaria. The patient was treated with a modification of ProMACE CYTABOM regimen and had prompt regression of the leukemia with associated acute tumor lysis. Renal, hepatic, and marrow failure predominated during a terminal course that ended 22 days after therapy was commenced, and at autopsy there was no evidence for leukemic cell infiltrate in the liver, spleen or marrow. The leukemic cells were large granular lymphocytes by light and electron microscopic criteria, and had the following immunophenotype: CD2+, DR+, Leu7+, NKH1+, CD11+, CD3-, CD5-, CD4-, CD8-, CD16-. The cells displayed high antibody- dependent cell-mediated cytotoxicity (ADCC) and NK activity, and had a high rate of spontaneous proliferation in vitro that was not augmented by phytohemagglutinin (PHA), concanavalin A (Con A), or pokeweed mitogen (PWM). Southern analysis of DNA from leukemic cells revealed normal germline arrangements for the beta and gamma chains of the T cell antigen receptor and immunoglobulin heavy chain genes. The majority of metaphases were clonally abnormal revealing consistent rearrangements involving extra material attached to the long arms of chromosomes 5 and 11.     

Defective function of lymphokine-activated killer cells and natural killer cells in patients with hepatocellular carcinoma

Lymphokine-activated killer activity and natural killer activity in hepatocellular carcinoma patients were assessed. Maximum lymphokine-activated killer activity was induced at 3 to 5 days of incubation, and lymphokine-activated killer activity tended to increase in a manner dose dependent of recombinant interleukin-2. However, the maximum increase of lymphokine-activated killer activity in hepatocellular carcinoma was not as high as that of normal subjects or liver cirrhosis patients. Lymphokine-activated killer activity was impaired in hepatocellular carcinoma as compared to that in normal subjects. Hepatocellular carcinoma seemed to consist of two groups: i.e. a high-lymphokine-activated killer activity group and a low-lymphokine-activated killer activity group. Reduction of natural killer activity was also observed in hepatocellular carcinoma as compared with that in normal subjects and patients with liver cirrhosis. No correlation could be demonstrated between natural killer activity and lymphokine-activated killer activity in normal subjects, liver cirrhosis patients and hepatocellular carcinoma patients. With regard to the presence of HBsAg or alpha-fetoprotein concentration in the sera, there was no significant difference in natural killer and lymphokine-activated killer activity in hepatocellular carcinoma patients. Patients with a small mass lesion showed a low lymphokine-activated killer activity, and depressed lymphokine-activated killer activity was not necessarily related to tumor size. In comparison with the high-lymphokine-activated killer group, the low-lymphokine-activated killer group showed a significant decrease in gamma-interferon production and a preserved function of indocyanine green clearance.     

Effect of estrogen on natural killer cells

Treatment of mice with sustained high levels of β-estradiol leads to a reduction in natural killer cell activity and genetic resistance to bone marrow transplantation. The loss of natural killing does not seem to result from either humoral or immune suppression. Natural killer cells are thought to depend on the bone marrow, and it is notable that estrogens reduce natural killing at approximately the same time that they produce a loss of marrow due to osteoproliferation. Similarly, mice with congenital osteopetrosis are deficient in natural killing. However, changes in natural killing during and after treatment with estrogen do not correspond directly to changes in marrow volume. Estrogens are known to exacerbate spontaneous autoimmunity in NZB/NZW mice. The relationship between this effect and the effect of estrogen on natural killing is not clear. When natural killing is lowered in NZB/NZW mice by the in vivo administration of ⁸⁹Sr, autoimmunity is reduced.     

Relationship of curative surgery on natural killer cell activity in colorectal cancer

PURPOSE: Aim of this study has been to evaluate natural killer (NK) activity in patients with colorectal tumors before and after curative surgery. METHODS: Forty colorectal cancer patients without distant metastases were stratified according to American Joint Committee on Cancer/International Union Against Cancer staging system into three categories: Stage I (n = 12), Stage II (n = 15), and Stage III (n = 13). All of them underwent curative resection, and there were no major postoperative complications. Venous blood samples were obtained preoperatively, at surgical wound closure, and on the 1st, 7th, and 21st postoperative days. Mononuclear cells were isolated over Ficoll-Hypaque ^? (Lymphoprep, Nycomed Pharma AS, Oslo, Norway) gradients, and NK activity was assayed by evaluation of cytotoxic response against K562 cells. Normal NK activity was achieved from 15 healthy donors. Percentage relative increments in relation to preoperative levels were calculated for every postoperative sample, and t- test was used for statistical evaluation. RESULTS: Before surgery, Stages II and III patients had lower levels of NK activity than healthy people (P < 0.05 and P < 0.001, respectively). NK activity always fell after surgery (Stage I: -18.48±11.42; Stage II: ?16.93±13.57; Stage III: ?35.29±12.03, at day 1 postsurgery) and appeared to rise slightly by the 21st postoperative day in Stage I patients (+4.87±12.41). Stage II, and especially Stage III, patients did show a significant recovery by the 21st postoperative day (+23.63±9.36 and +43.19±13.34, respectively). At this time, NK activity in these two groups was not significantly lower than in normal subjects (P > 0.05). CONCLUSION: NK activity is depressed in colorectal cancer patients in relation to progression of illness, even at locoregional stages. Curative resection of tumors at Stages II and III has promoted a recovery of NK activity in patients with uneventful postoperative courses.     

肿瘤浸润性自然杀伤细胞在免疫治疗中的研究进展

自然杀伤(NK)细胞是一种具有强大细胞毒性和活性的先天淋巴细胞。基于NK细胞的免疫疗法在血液系统肿瘤的治疗中取得显著疗效,但在实体恶性肿瘤的治疗中疗效较低。该文就NK细胞的功能、表型及其肿瘤免疫治疗的研究进展作一综述。     

NKT细胞在肝脏疾病中的作用

自然杀伤T细胞(natllral killer T cells.NKT细胞)是一种同时具有NK细胞和T细胞部分表型及功能的细胞亚群.他能将先天性免疫应答和获得性免疫应答连接起来,限制性识别CDld-糖脂抗原、活化后迅速分泌大量细胞因子从而调节机体的免疫应答.人体的肝脏内富含NKT细胞,因此,NKT细胞在肝脏中的作用引起了人们的广泛兴趣.