Shaping of NK cell subsets by aging

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Human monocyte heterogeneity: interleukin 1 and prostaglandin E2 production by separate subsets

Human peripheral blood monocytes were separated into four different subpopulations by means of a discontinuous bovine serum albumin gradient. Of the least dense population, 7% were present in fraction A, 11% in fraction B, 28% in fraction C and of the most dense, 34% were in fraction D. The rest (17%) of the recovered cells sedimented as a pellet, of which 95% were dead. The monocytes of fraction D (= greater than or equal to 1.075 kg/l) were major interleukin 1 (IL 1) producers and their presence enhanced immunoglobulin synthesis in vitro. Fraction C (= greater than or equal to 1.070 kg/l) were the major prostaglandin E2 (PGE2) producers and demonstrated suppressor activity on in vitro IgG and IgM synthesis. Fractions A and B had minimal production of either IL 1 or PGE2 and lesser effects on the IgG and IgM synthesis. These data demonstrate functional heterogeneity of peripheral blood monocytes with respect to production of both IL 1 and PGE2 as well as accessory cells for immunoglobulin synthesis.     

Human tumor-induced and naturally occurring Treg cells differentially affect NK cells activated by either IL-2 or target cells

NK cells play a crucial role in the eradication of tumor cells. Naturally occurring (n) Treg cells and induced (i) Treg cells are two distinct Treg subsets. While the interaction of nTreg cells with NK cells has been investigated in the past, the role of tumor iTreg cells in the modulation of NK-cell function remains unclear. Tumor iTreg cells were generated from CD4(+) CD25(-) T cells in the presence of autologous immature DCs, head and neck cancer cells and IL-2, IL-10, and IL-15. The effect of iTreg cells and nTreg cells on the expression of NKG2D, NKp44, CD107a, and IFN-γ by NK cells, as well as NK tumor-cytolytic activity, were investigated. iTreg cells - similar to recombinant TGF-β and nTreg cells - inhibited IL-2-induced activation of NK cells in the absence of target cell contact. Surprisingly, and in contrast to nTreg cells, iTreg cells enhanced NK-cell activity elicited by target cell contact. The cytolytic activity of NK cells activated by iTreg cells was mediated via perforin and FasL. We conclude that tumor iTreg cells inhibited IL-2-mediated NK-cell activity in the absence of target cells, whereas the tumoricidal activity of NK cells was enhanced by iTreg cells. Our data suggest a complex, previously not recognized, differential regulation of human NK activity by iTreg cells in the tumor microenvironment.     

Different natural killer (NK) receptor expression and immunoglobulin E (IgE) regulation by NK1 and NK2 cells

Many studies concerning the role of T cells and cytokines in allergy have been performed, but little is known about the role of natural killer (NK) cells. Accordingly, the expression of co-stimulatory, inhibitory and apoptosis receptors, cytokine profiles and their effect on immunoglobulin isotypes were investigated in polyallergic atopic dermatitis (AD) patients with hyper immunoglobulin E (IgE) and healthy individuals. AD patients showed significantly decreased peripheral blood NK cells compared to healthy individuals. Freshly isolated NK cells of polyallergic patients spontaneously released higher amounts of interleukin (IL)-4, IL-5, IL-13 and interferon (IFN)-gamma compared to healthy individuals. NK cells were differentiated to NK1 cells by IL-12 and neutralizing anti-IL-4 monoclonal antibodies (mAb), and to NK2 cells by IL-4 and neutralizing anti-IL-12 mAb. Following IL-12 stimulation, NK cells produced increased levels of IFN-gamma and decreased IL-4. In contrast, stimulation of NK cells with IL-4 inhibited IFN-gamma, but increased IL-13, production. The effect of NK cell subsets on IgE regulation was examined in co-cultures of in vitro differentiated NK cells with peripheral blood mononuclear cells (PBMC) or B cells. NK1 cells significantly inhibited IL-4- and soluble CD40-ligand-stimulated IgE production; however, NK2 cells did not have any effect. The inhibitory effect of NK1 cells on IgE production was blocked by neutralization of IFN-gamma. Except for CD40, NK cell subsets showed different expression of killer-inhibitory receptors and co-stimulatory molecules between the polyallergic and healthy subjects. These results indicate that human NK cells show differences in numbers, surface receptor and cytokine phenotypes and functional properties in AD.     

Human NK cells,their receptors and function

NK cells are cytotoxic components of innate lymphoid cells (ILC) that provide a first line of defense against viral infections and contribute to control tumor growth and metastasis. Their function is finely regulated by an array of HLA-specific and non-HLA-specific inhibitory and activating receptors which allow to discriminate between healthy and altered cells. Human NK cells gained a major attention in recent years because of the important progresses in understanding their biology and of some promising data in tumor therapy. In this review, we will outline well-established issues of human NK cells and discuss some of the open questions, debates, and recent advances regarding their origin, differentiation, and tissue distribution. Newly defined NK cell specializations, including the impact of inhibitory checkpoints on their function, their crosstalk with other cell types, and the remarkable adaptive features acquired in response to certain virus infections will also be discussed.     

Circulating NK cells and their subsets in Behçet's disease

Behçet's disease (BD) is an autoinflammatory, chronic relapsing/remitting disease of unknown aetiology with both innate and acquired immune cells implicated in disease pathogenesis. Peripheral blood natural killer (NK) cells and their CD56^Dim/CD56^Bright subsets were surface phenotyped using CD27 and CD16 surface markers in 60 BD patients compared to 60 healthy controls (HCs). Functional potential was assessed by production of interferon (IFN)‐γ, granzyme B, perforin and the expression of degranulation marker CD107a. The effects of disease activity (BD^Active versus BD^Quiet) and BD medication on NK cells were also investigated. Peripheral blood NK cells (P < 0·0001) and their constituent CD56^Dim (P < 0·0001) and CD56^Bright (P = 0·0015) subsets were depleted significantly in BD patients compared to HCs, and especially in those with active disease (BD^Active) (P < 0·0001). BD patients taking azathioprine also had significantly depleted NK cells compared to HCs (P < 0·0001). A stepwise multivariate linear regression model confirmed BD activity and azathioprine therapy as significant independent predictor variables of peripheral blood NK percentage (P < 0·001). In general, CD56^Dim cells produced more perforin (P < 0·0001) and granzyme B (P < 0·01) expressed higher CD16 levels (P < 0·0001) compared to CD56^Bright cells, confirming their increased cytotoxic potential with overall higher NK cell CD107a expression in BD compared to HCs (P < 0·01). Interestingly, IFN‐γ production and CD27 expression were not significantly different between CD56^Dim/CD56^Bright subsets. In conclusion, both BD activity and azathioprine therapy have significant independent depletive effects on the peripheral blood NK cell compartment.     

开胸患者围手术期T细胞亚群及NK细胞的动态变化及意义

目的 :探讨开胸患者围手术期间细胞免疫功能的动态变化及其临床意义。方法 :应用流式细胞仪检测 4 5例开胸患者术前、术后 1、3、5及 7天的外周血T细胞亚群 (CD3、CD4、CD8、CD4 CD8)及NK细胞水平 ,并对 4 5例患者随机分组 ,比较纵隔、肺、食管贲门手术组围手术期T细胞亚群及NK细胞的变化。结果 :与术前相比开胸患者术后 1天CD4 CD8和术后 3天CD4降低。其中 ,纵隔肿瘤手术组术后 1天CD4 CD8和术后 3天CD4降低 ;肺部手术组合术后 1天及 7天CD8和术后 5天NK细胞降低 ,术后 5天CD3及术后 7天CD4 CD8升高 ;食管贲门手术组术后 1天CD4 CD8降低 ,术后 7天CD3及CD4升高。具有统计学意义 (P <0 0 5 )。结论 :开胸患者术后细胞免疫功能呈现受抑制状态而降低 ,主要出现在术后第 1～ 3天 ,术后第 5～ 7天开始恢复。因患者疾病种类及手术类型不同 ,细胞免疫功能受抑制持续的时间及恢复开始的时间不尽相同。食管贲门手术患者术后细胞免疫功能受抑严重且恢复较慢 ,肺部手术患者次之 ,纵隔肿瘤手术患者较轻。开胸患者术后 1周内应用抗菌素防治感染及适当免疫增强治疗是必要的。     

人外周血NK细胞纯化方法的初步比较

目的：初步探讨ＮＫ细胞的纯化方法并在基础上研究其生物学特性。方法：分别利用Ｐａｎｎｉｎｇ法、补体裂解法、绵羊红细胞花环法对ＮＫ细胞进行纯化并利用流式细胞仪检测其纯度，利用ＭＴＴ法检测ＮＫ细胞对Ｋ５６２细胞的杀伤特性，利用ＲＴ－ＰＣＲ检测ＮＫ细胞在ＩＬ－２作用下ＩＦＮ－γ基因表达情况。结果：ＮＫ细胞的纯度由纯化前１０％左右提高到５５．７５％，不同纯化方法有所不同，纯化ＮＫ细胞较天然人ＰＢＭＣ对靶细胞     

NK cells and type 1 diabetes

Type 1 diabetes (T1D) is characterized by an immuno-mediated progressive destruction of the pancreatic beta cells. Due to the ability of NK cells to kill target cells as well as to interact with antigen-presenting and T cells, it has been suggested that they could be involved in one or multiple steps of the immune-mediated attack that leads to T1D. Abnormalities in the frequency and activity of NK cells have been described both in animal models and patients with T1D. Some of these alterations are linked to its onset while others seem to be a consequence of the disease. Here, we discuss the main characteristics of NK cells and review the studies that investigated the role of NK cells in T1D, both in mouse models and humans.     

Modulation of human NK cells by interferon and prostaglandin E2

Our studies have shown that stimulation of human natural killer (NK) cells by poly I:C does not depend on or require monocytes. In contrast, the presence of monocytes in a mixed population of mononuclear cells stimulated by poly I:C suppresses NK activity. The suppression can be partially overcome if indomethacin (10(-6) M) is added to the culture during stimulation. Culture supernatants from poly I:C stimulated monocytes do not have detectable levels of anti-viral activity but contained appreciable amounts of PGE2. Our results offer an explanation as to how NK cells may protect themselves from suppression by PGE2. We have demonstrated that IFN-activated NK cells become resistant to PGE2-mediated suppression; moreover the suppression does not require cells other than the large granular lymphocytes, the major effector cell type for NK. Taken together, the data suggest that stimulation of NK cells is dependent on and regulated by the relative levels of interferon produced by lymphocytes and PGE2 produced by monocytes.     

Assessment of Cmv1 candidates by genetic mapping and in vivo antibody depletion of NK cell subsets.

The mouse chromosome 6 locus Cmv1 controls resistance to infection with murine cytomegalovirus (MCMV). We have previously shown that Cmv1 is tightly linked to members of the NK gene complex (NKC) including the Ly49 gene family. To assess the candidacy of individual NKC members for the resistance locus, first we followed the co-segregation of Cd94, Nkg2d, and the well-characterized Ly49a, Ly49c and Ly49g genes with respect to Cmv1 in pre-existing panels of intraspecific backcross mice. Gene order and intergene distances (in cM) were: centromere-Cd94/Nkg2d-(0.05)-Ly49a/Ly49c/Ly49 g/Cmv1-(0. 3)-Prp/Kap/D6Mit13/111/219. This result excludes Cd94 and Nkg2d as candidates whereas it localizes the Ly49 genes within the minimal genetic interval for Cmv1. Second, we monitored the cell surface expression of individual Ly49 receptors in MCMV-infected mice over 2 weeks. The proportion of Ly49C(+) and Ly49C/I(+) cells decreased, the proportion of Ly49A(+) and Ly49G2(+) remained constant, and the cell surface density of Ly49G2 increased during infection, suggesting that NK cell subsets might have different roles in the regulation of MCMV infection. Third, we performed in vivo antibody depletion of specific NK cell subsets. Depletion with single antibodies did not affect the resistant phenotype suggesting that Ly49A(+), Ly49C(+), Ly49G2(+) and Ly49C/I(+) populations are not substantial players in MCMV resistance, and arguing for exclusion of the respective genes as candidates for Cmv1. In contrast, mice depleted with combined antibodies showed an intermediate phenotype. Whether residual NK cells, post-depletion, belong to a particular subset expressing another Ly49 receptor, or a molecule encoded by a yet to be identified gene of the NKC, is discussed.     

Human suppressor cells: evidence of functionally distinct subsets

Human suppressor cells (SC) differing in both kinetic characteristics and degree of specificity were induced in vitro either by Concanavalin A (CON A) (10 μg/ml) or by repeated stimulation with allogeneic cells. CON A SC caused a characteristic early peak in blastogenesis (Day 2) when cocultured with fresh autologous cells in the presence of either CON A or allogeneic cells, although CON A SC alone did not respond to these stimuli. This early augmented response fell rapidly to values 50–90% below positive controls by the usual optimal day for the particular stimulus. Treatment with 5-bromodeoxyuridine and light during rapid proliferation ablated the early responses but increased the later responses (i.e., reduced the suppression). The cells mediating both the early rise and late suppression were found to belong to a subset of T cells that lost their ability to form SRBC rosettes (theophylline sensitive) in the presence of the phosphodiesterase inhibitor, theophylline, and were inactivated by mitomycin C. In contrast, SC induced by repeated allogeneic stimulation were suppressive in MLC but not CON A cultures, did not initiate early blastogenesis in the presence of naive cells and were partially mitomycin resistant. The mitomycin resistant SC induced by allogeneic stimulation are found in the theophylline resistant T-cell subset. These data are consistent with a model of human SC differentiation in which at least two subsets may be present: (1) a mitomycin sensitive, nonspecific cell that participates in an obligatory early autologous recognition event (induction?) and (2) a later occurring, more mitomycin resistant effector cell that appears to acquired specfficity for the response that it affects.     

Selective depletion of CD56(dim) NK cell subsets and maintenance of CD56(bright) NK cells in treatment-naive HIV-1-seropositive individuals

Human immunodeficiency virus-1 (HIV-1) infected patients show a gradual loss of natural killer (NK) cells that correlates with disease progression. However, the effect of HIV-1 infection on different NK cell subsets has not been fully characterized. In healthy individuals most NK cells are CD3^–CD56⁺ and two different subpopulations, CD56^dim and CD56^bright, can be distinguished by the mean fluorescence intensity. Although it was originally suggested that CD56^bright NK cells represent the precursors of the CD56^dim subpopulation, recent cumulative data indicate that CD56^bright and CD56^dim NK cells are phenotypically, functionally, and developmentally different NK cell subsets. In this study, the analysis of CD56^bright and CD56^dim NK subsets showed that neither the number nor the phenotype of CD56^bright NK cells were significantly altered in treatment-naive HIV-1-infected individuals, whereas the number of CD56^dim NK cells was decreased. We also have studied NK cell subsets defined by the expression of CD56 in combination with CD16, CD161, or CD94 molecules. Our results demonstrated a preferential decrease of CD3^–CD56⁺ NK cells coexpressing CD16 and CD161 but lacking CD94 molecules. On the contrary an increased percentage of NK cells that do not express CD56 molecules but express CD16, CD161, or CD94 was also found in HIV-1-infected individuals. As it has been proposed that these CD56-negative NK cells expressing other NK cell receptors represent immature NK cells with low cytolytic capacity, our results support that a defective differentiation from immature CD56 negative NK cells to mature CD56^dim NK cells occurs in HIV-1 infection.     

Human NK cells: their ligands, receptors and functions

Summary: The expression, or lack thereof, of class I MHC glycoproteins has a marked influence on natural killer cell function. Cells which do not express class I MHC molecules are susceptible to lysis by NK cells, and transfection of these targets with class I MHC genes can render these cells resistant to NK attack. This inhibition of NK-killing is mediated by a novel family of receptors expressed mainly on NK cells, but also found on some T-cells. The function of these class I MHC binding receptors when expressed on T-cells is discussed also and a novel co-stimulatory activity of NKAR described. Lastly, a novel mechanism by which human cytomegalovirus evades immune surveillance by NK cells is documented.     

非霍奇金淋巴瘤患者T细胞亚群、NK细胞检测的临床意义

目的：研究非霍奇金淋巴瘤（NHL）患者外周血T淋巴细胞亚群、NK细胞检测结果的变化与该病的关系及与慢性淋巴腺炎患者细胞免疫功能的不同变化。方法：采用流式细胞仪（FCM）检测非霍奇金淋巴瘤（NHL）患者、慢性淋巴腺炎及正常人外周血T淋巴细胞亚群比例、NK细胞的变化。结果：非雹奇金淋巴瘤患者与正常人比较总的T淋巴细胞、辅助性T淋巴细胞及CD4^＋／CD8^＋比值明显下降（P〈0．05），细胞毒性T淋巴细胞明显升高（P〈0．05），NK细胞则无明显变化（P〉0．05）。非霍奇金淋巴瘤患者与慢性淋巴腺炎患者比较，细胞毒性T淋巴细胞、NK细胞明显升高（P〈0.05），而总的T淋巴细胞、辅助性T淋巴细胞无明显改变（P〉0．05），CD4^＋／CD8^＋比值略有下降但无明显统计学意义。结论：非霍奇金淋巴瘤患者细胞免疫功能明显受到抑制，T细胞亚群及NK细胞的检测对NHL的诊断、治疗、预后判断有一定的临床价值。