Kegg Pathway: Natural killer cell mediated cytotoxicity

Curr Biol. 2009 Nov 11;
Butler B, Cooper JA

BACKGROUND: Several actin nucleators, including Arp2/3 and various formins, control numerous cytoskeletal-based functions in vivo. RESULTS: We investigated the relative roles of these nucleators. As a model system, we used Natural killer (NK) lymphocytes, which display a wide range of cytoskeletal-based functions that culminate in the lysis of target cells. NK cells lacking either Arp2/3 or the formin hDia1 were ineffective in target cell lysis, but for distinct reasons. Loss of Arp2/3 function led to defects in cell adhesion and actin assembly at the junction with the target cell (the lytic synapse). In contrast, loss of hDia1 did not disrupt actin assembly at the lytic synapse. Instead, loss of hDia1 led to perturbations in the microtubule cytoskeleton, including the targeting of microtubules to the lytic synapse. CONCLUSIONS: These studies reveal novel distinctions and relationships among the functions of Arp2/3, formins, and microtubules in cells. Notably, a formin mediates the capture of microtubules at the cell periphery.

Acta Haematol. 2009 Nov 12; 123(1): 21-29
Richardson SJ, Eve HE, Copplestone JA, Dyer MJ, Rule SA

Thalidomide and lenalidomide are immunomodulatory drugs that show promise in mantle cell lymphoma (MCL). In this study, their potential mechanisms of action against MCL cells were investigated, both alone and in combination with rituximab. Thalidomide, lenalidomide and rituximab have no direct effect on MCL cell viability. However, both immunomodulatory drugs indirectly affect viability by enhancing peripheral blood mononuclear cell-mediated cytotoxicity, with lenalidomide inducing significantly higher levels of toxicity than thalidomide. Rituximab induces both complement-dependent and antibody-dependent cellular cytotoxicity (ADCC) against MCL cells. Rituximab-induced ADCC is enhanced by lenalidomide and, to a lesser extent, thalidomide. Preliminary in vivo findings in MCL patients treated with thalidomide support a role for Natural killer cells in the efficacy of these drugs. In conclusion, our data support a role for immunomodulatory drugs in the treatment of MCL.

Blood. 2009 Nov 6;
Yu J, Mao HC, Wei M, Hughes T, Zhang J, Park IK, Liu S, McClory S, Marcucci G, Trotta R, Caligiuri MA

Human CD56(bright) Natural killer (NK) cells possess little or no killer immunoglobulin-like receptors (KIR), high IFN-gamma production, but little cytotoxicity. CD56(dim) NK cells have high KIR expression, produce little IFN-gamma, yet display high cytotoxicity. We hypothesized that if human NK maturation progresses from a CD56(bright) to a CD56(dim) phenotype, an intermediary NK cell must exist which demonstrates more functional overlap than these two subsets, and we utilized CD94 expression to test our hypothesis. CD94(high)CD56(dim) NK cells express CD62L, CD2, and KIR at levels between CD56(bright) and CD94(low)CD56(dim) NK cells. CD94(high)CD56(dim) NK cells produce less monokine-induced IFN-gamma than CD56(bright) NK cells but much more than CD94(low)CD56(dim) NK cells due to differential IL-12-mediated STAT4 phosphorylation. CD94(high)CD56(dim) NK cells possess a higher level of granzyme B and perforin expression and CD94-mediated redirected killing than CD56(bright) NK cells but lower than CD94(low)CD56(dim) NK cells. Collectively, our data suggest that density of CD94 surface expression on CD56(dim) NK cells identifies a functional and likely developmental intermediary between CD56(bright) and CD94(low)CD56(dim) NK cells. This supports the notion that in vivo, human CD56(bright) NK cells progress through a continuum of differentiation that ends with a CD94(low)CD56(dim) phenotype.

Cancer Res. 2009 Oct 15; 69(20): 8058-66
Reim F, Dombrowski Y, Ritter C, Buttmann M, Häusler S, Ossadnik M, Krockenberger M, Beier D, Beier CP, Dietl J, Becker JC, Hönig A, Wischhusen J

Although trastuzumab (Herceptin) has substantially improved the overall survival of patients with mammary carcinomas, even initially well-responding tumors often become resistant. Because Natural killer (NK) cell-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) is thought to contribute to the therapeutic effects of trastuzumab, we have established a cell culture system to select for ADCC-resistant SK-OV-3 ovarian cancer and MCF7 mammary carcinoma cells. Ovarian cancer cells down-regulated HER2 expression, resulting in a more resistant phenotype. MCF7 breast cancer cells, however, failed to develop resistance in vitro. Instead, treatment with trastuzumab and polyclonal NK cells resulted in the preferential survival of individual sphere-forming cells that displayed a CD44(high)CD24(low) "cancer stem cell-like" phenotype and expressed significantly less HER2 compared with non-stem cells. Likewise, the CD44(high)CD24(low) population was also found to be more immunoresistant in SK-BR3, MDA-MB231, and BT474 breast cancer cell lines. When immunoselected MCF7 cells were then re-expanded, they mostly lost the observed phenotype to regenerate a tumor cell culture that displayed the initial HER2 surface expression and ADCC-susceptibility, but was enriched in CD44(high)CD24(low) cancer stem cells. This translated into increased clonogenicity in vitro and tumorigenicity in vivo. Thus, we provide evidence that the induction of ADCC by trastuzumab and NK cells may spare the actual tumor-initiating cells, which could explain clinical relapse and progress. Moreover, our observation that the "relapsed" in vitro cultures show practically identical HER2 surface expression and susceptibility toward ADCC suggests that the administration of trastuzumab beyond relapse might be considered, especially when combined with an immune-stimulatory treatment that targets the escape variants.

Immunology. 2009 Sep 9;
Schuster P, Donhauser N, Pritschet K, Ries M, Haupt S, Kittan NA, Korn K, Schmidt B

Summary Human plasmacytoid dendritic cells (PDC) are crucial for innate and adaptive immune responses against viral infections, mainly through production of type I interferons. Evidence is accumulating that PDC surface receptors play an important role in this process. To investigate the PDC phenotype in more detail, a chip-based expression analysis of surface receptors was combined with respective flow cytometry data obtained from fresh PDC, PDC exposed to interleukin-3 (IL-3) and/or herpes simplex virus type 1 (HSV-1). CD156b, CD229, CD305 and CD319 were newly identified on the surface of PDC, and CD180 was identified as a new intracellular antigen. After correction for multiple comparisons, a total of 33 receptors were found to be significantly regulated upon exposure to IL-3, HSV-1 or IL-3 and HSV-1. These were receptors involved in chemotaxis, antigen uptake, activation and maturation, migration, apoptosis, cytotoxicity and costimulation. Infectious and ultraviolet-inactivated HSV-1 did not differentially affect surface receptor regulation, consistent with the lack of productive virus infection in PDC, which was confirmed by HSV-1 real-time polymerase chain reaction and experiments involving autofluorescing HSV-1 particles. Viral entry was mediated at least in part by endocytosis. Time-course experiments provided evidence of a co-ordinated regulation of PDC surface markers, which play a specific role in different aspects of PDC function such as attraction to inflamed tissue, antigen recognition and subsequent migration to secondary lymphatic tissue. This knowledge can be used to investigate PDC surface receptor functions in interactions with other cells of the innate and adaptive immune system, particularly Natural killer cells and cytotoxic T lymphocytes.

Hepatology. 2009 Nov; 50(5): 1606-16
Zhang M, Han Y, Han C, Xu S, Bao Y, Chen Z, Gu Y, Xia D, Cao X

The beta2 integrins play a key role in inflammation and immune responses. The beta2 integrin CD11b has been shown recently to be important in the maintenance of tolerance; however, the underlying mechanisms remain to be fully understood. Natural killer (NK) cells are an important effector of innate immunity but are also a regulator of adaptive immune response. How the activating and inhibitory signals are balanced to determine NK cell function needs to be further identified. CD11b expression was dramatically up-regulated on NK cells once they matured and became activated; therefore, we investigated the role of inducible CD11b in the regulation of NK cells. Neutralizing anti-CD11b antibody enhanced cytotoxicity, interferon-gamma (IFN-gamma) and granzyme B production of Toll-like receptor 3 (TLR3)-triggered NK cells. CD11b-deficient NK cells stimulated with or without the TLR3 ligand polyinosinic:polycytidylic acid [poly(I:C)] exhibited more potent cytotoxicity, and higher production of IFN-gamma and granzyme B. Through in vivo depletion of NK cells and adoptive transfer of CD11b-deficient NK cells, we demonstrated that CD11b-mediated suppression of NK cell function was responsible for attenuation of poly(I:C)-induced acute hepatitis by CD11b. CONCLUSION: Our findings demonstrate that CD11b negatively regulates NK cell activation and thus attenuates poly(I:C)-induced acute hepatitis. Our study provides a new mechanistic explanation for maintenance of tolerance and control of inflammation by CD11b.

Nanotechnology. 2009 Nov 4; 20(44): 445101
Ji Z, Zhang D, Li L, Shen X, Deng X, Dong L, Wu M, Liu Y

The hepatotoxicity of two types of multi-walled carbon nanotubes (MWCNTs), acid-oxidized MWCNTs (O-MWCNTs) and Tween-80-dispersed MWCNTs (T-MWCNTs), were investigated with Kunming mice exposed to 10 and 60 mg kg(-1) by intravenous injection for 15 and 60 d. Compared with the PBS group, the body-weight gain of the mice decreased and the level of total bilirubin and aspartate aminotransferase increased in the MWCNT-exposed group with a significant dose-effect relationship, while tumor necrosis factor alpha level did not show significant statistical change within 60 d. Spotty necrosis, inflammatory cell infiltration in portal region, hepatocyte mitochondria swelling and lysis were observed with a significant dose-effect relationship in the MWCNT groups. Liver damage of the T-MWCNT group was more severe than that of the O-MWCNT group according to the Roenigk classification system. Furthermore, T-MWCNTs induce slight liver oxidative damage in mice at 15 d, which was recovered at 60 d. Part of the gene expressions of mouse liver in the MWCNT groups changed compared to the PBS group, including GPCRs (G protein-coupled receptors), cholesterol biosynthesis, metabolism by cytochrome P450, Natural-killer-cell-mediated cytotoxicity, TNF- alpha, NF-kappaB signaling pathway, etc. In the P450 pathway, the gene expressions of Gsta2 (down-regulated), Cyp2B19 (up-regulated) and Cyp2C50 (down-regulated) had significant changes in the MWCNT groups. These results show that a high dose of T-MWCNTs can induce hepatic toxicity in mice while O-MWCNTs seem to have less toxicity.

J Immunol. 2009 Oct 15; 183(8): 4921-30
Carlsten M, Norell H, Bryceson YT, Poschke I, Schedvins K, Ljunggren HG, Kiessling R, Malmberg KJ

The activating NK cell receptor DNAX accessory molecule-1 (DNAM-1) contributes to tumor immune surveillance and plays a crucial role in NK cell-mediated recognition of several types of human tumors, including ovarian carcinoma. Here, we have analyzed the receptor repertoire and functional integrity of NK cells in peritoneal effusions from patients with ovarian carcinoma. Relative to autologous peripheral blood NK cells, tumor-associated NK cells expressed reduced levels of the DNAM-1, 2B4, and CD16 receptors and were hyporesponsive to HLA class I-deficient K562 cells and to coactivation via DNAM-1 and 2B4. Moreover, tumor-associated NK cells were also refractory to CD16 receptor stimulation, resulting in diminished Ab-dependent cellular cytotoxicity against autologous tumor cells. Coincubation of NK cells with ovarian carcinoma cells expressing the DNAM-1 ligand CD155 led to reduction of DNAM-1 expression. Therefore, NK cell-mediated rejection of ovarian carcinoma may be limited by perturbed DNAM-1 expression on tumor-associated NK cells induced by chronic ligand exposure. Thus, these data support the notion that tumor-induced alterations of activating NK cell receptor expression may hamper immune surveillance and promote tumor progression.

Toxicol Appl Pharmacol. 2009 Dec 15; 241(3): 253-9
Burchiel SW, Mitchell LA, Lauer FT, Sun X, McDonald JD, Hudson LG, Liu KJ

In these studies the immunotoxicity of arsenic trioxide (ATO, As(2)O(3)) was evaluated in mice following 14 days of inhalation exposures (nose only, 3 h per day) at concentrations of 50 microg/m(3) and 1 mg/m(3). A biodistribution analysis performed immediately after inhalation exposures revealed highest levels of arsenic in the kidneys, bladder, liver, and lung. Spleen cell levels were comparable to those found in the blood, with the highest concentration of arsenic detected in the spleen being 150 microg/g tissue following the 1 mg/m(3) exposures. No spleen cell cytotoxicity was observed at either of the two exposure levels. There were no changes in spleen cell surface marker expression for B cells, T cells, macrophages, and Natural killer (NK) cells. There were also no changes detected in the B cell (LPS-stimulated) and T cell (Con A-stimulated) proliferative responses of spleen cells, and no changes were found in the NK-mediated lysis of Yac-1 target cells. The primary T-dependent antibody response was, however, found to be highly susceptible to ATO suppression. Both the 50 microg/m(3) and 1 mg/m(3) exposures produced greater than 70% suppression of the humoral immune response to sheep red blood cells. Thus, the primary finding of this study is that the T-dependent humoral immune response is extremely sensitive to suppression by ATO and assessment of humoral immune responses should be considered in evaluating the health effects of arsenic containing agents.

Acta Microbiol Immunol Hung. 2009 Sep; 56(3): 199-210
Ongrádi J, Stercz B, Kövesdi V, Vértes L

The sharp increase of life expectancy and the increasing ratio of ageing population pose new challenges for the public health system. The elderly suffer from more frequent and severe infections than young people. Theoretically, vaccination could protect the elderly against several infectious diseases, but due to their age-related immune impairment, vaccination might fail in many cases. Instead of ineffective vaccination campaigns, exploration and restoration of age-dependent dysregulation of their immune functions have to be placed into the focus of recent research. Frequent comorbidities in these people augment immune defects. Immunosenescence affects both the innate and adaptive immunity. Disturbances in macrophage-derived cytokine release and reduction of the Natural killer cell mediated cytotoxicity lead to increased frequency of respiratory, gastrointestinal and skin infections. Although the humoral immunity retains most of its original activity through life span, ageing dampens the ability of B cells to produce antibodies against novel antigens. Age-related declination of the cellular immunity is the consequence of thymic atrophy, reduced output of new T lymphocytes, accumulation of anergic memory cells, deficiencies in the cytokine production and uncertain antigen presentation. Persistent infection by different herpesviruses and other parasites contribute to the loss of immunosurveillance and premature exhaustion of T cells.

Int Immunopharmacol. 2009 Dec; 9(13-14): 1555-61
Lee CH, Kim JK, Kim HY, Park SM, Lee SM

The immunomodulatory effects of Korean mistletoe lectin (KML), one of the major active components in Viscum album L. var. coloratum, were investigated in vitro in immune cell proliferation and Natural killer (NK) cell- and macrophage-mediated cytotoxicity, and in vivo in the forced swim test and cold stress. In mitogen-induced lymphocyte proliferation of murine splenocytes, concanavalin A and lipopolysaccharide significantly increased the proliferation of T cell and B cell lymphocytes, respectively. KML exposure increased lymphocyte proliferation in response to mitogen. KML also increased the splenic NK cell and macrophage activities in vitro. Exposure to KML increased production of cytokines such as interleukin-1 and interleukin-6 by macrophages. Two-week treatment with KML (30, 100, 300 and 600 microg/kg) increased the recruitment of lymphocytes, monocytes and macrophages. In the forced swim test, the immobility time was significantly attenuated by treatment with KML (300 and 600 microg/kg). In a cold stress experiment, spleen and thymus weight increased in KML-treated mice, while the weight of adrenal gland was lower than that in vehicle-treated mice. The levels of serum aminotransferases, lactate dehydrogenase and alkaline phosphatase were decreased by KML treatment. KML treatment also induced increases in the percentages of CD4(+) and CD8(+) cells in thymus. Our results suggest that KML enhances the immune system through modulation of lymphocytes, NK cells, and macrophages.

J Appl Physiol. 2009 Sep 17;
Wang JS, Wu CK

Natural killer cells (NKs) are important to the clearance of transformed cells. This investigation elucidates how systemic hypoxia influences mobilization of the NK subsets and cytotoxicity of NKs to nasopharyngeal carcinoma cells (NPCs) during exercise. Sixteen sedentary males performed six distinct experimental tests in an air-conditioned normobaric hypoxia chamber: high-intensity exercise (HE; up to VO2max) under 21%O2, moderate-intensity exercise (ME; 50%VO2max for 30 min) under 12%, 15% and 21%O2, and breathing 12% and 15%O2 for 30 min at rest. The results demonstrated that 21%O2 HE, but not ME, increased cellular perforin/granzyme B/interferon-gamma levels in NKs and interferon-gamma concentration in NK-NPC co-incubation, as well as, promoted capacity of NKs to bind to NPCs and NK-induced CD95 expression and phosphotidylserine exposure of NPCs. However, the HE simultaneously increased percentages of the replicative senescent (CD57(+) and CD28(-)) NKs and the NKs with inhibitory receptors (KLRG1+) that entered the bloodstream from peripheral tissues. Breathing 12% and 15%O2 at rest did not cause redistribution of the NK subset populations, and the two hypoxic interventions unchanged NK-induced NPC apoptotic responses. Although both 12% and 15%O2 ME increased NK count, perforin/granzyme B/interferon-gamma levels, NK-NPC binding and NK-induced CD95 expression and apoptosis of NPC, only 12%O2 ME increased percentages of the NKs with CD57(+)/CD28(-)/KLRG1(+) in blood. Therefore, we conclude that systemic hypoxic exposure affects redistribution of NK subsets and anti-NPC cytotoxicity of NKs during exercise in a concentration-dependent manner. Moreover, exposure to 12%O2 promotes the NK cytotoxicity with mobilizing the replicative senescent/inhibitory NKs into the bloodstream during ME. Key words: oxygen, physical activity, leukocyte, carcinoma cell.

Nat Immunol. 2009 Oct; 10(10): 1118-24
Gascoyne DM, Long E, Veiga-Fernandes H, de Boer J, Williams O, Seddon B, Coles M, Kioussis D, Brady HJ

Natural killer (NK) cells are a subset of lymphocytes crucial for innate immunity and modification of adaptive immune responses. In contrast to commitment to the T cell or B cell lineage, little is known about NK cell lineage commitment. Here we show that the basic leucine zipper (bZIP) transcription factor E4BP4 (also called NFIL3) is essential for generation of the NK cell lineage. E4BP4-deficient mice (Nfil3(-/-); called 'E4bp4(-/-)' here) had B cells, T cells and NKT cells but specifically lack NK cells and showed severely impaired NK cell-mediated cytotoxicity. Overexpression of E4bp4 was sufficient to increase NK cell production from hematopoietic progenitor cells. E4BP4 acted in a cell-intrinsic manner 'downstream' of the interleukin 15 receptor (IL-15R) and through the transcription factor Id2. E4bp4(-/-) mice may provide a model for definitive analysis of the contribution of NK cells to immune responses and pathologies.

Cancer Res. 2009 Oct 1; 69(19): 7775-83
Kopp HG, Placke T, Salih HR

Natural killer (NK) cells play an important role in cancer immunosurveillance and may prevent tumor progression and metastasis due to their ability to mediate direct cellular cytotoxicity and by releasing immunoregulatory cytokines, which shape adaptive immune responses. Their reactivity is governed by various activating and inhibitory molecules expressed on target cells and reciprocal interactions with other hematopoietic cells such as dendritic cells. In mice, thrombocytopenia inhibits metastasis, and this is reversed by NK cell depletion, suggesting that platelets are an important additional player in NK cell-tumor interaction. Moreover, it has been shown that metastasizing tumor cells do not travel through the blood alone but are rapidly coated by platelets. However, the knowledge about the molecular mechanisms by which platelets influence NK cells is fragmentary at best. Here we show that platelet-derived soluble factors, secreted on coating of tumor cells or after stimulation with classic platelet agonists, impair NK cell antitumor reactivity resulting in diminished granule mobilization, cytotoxicity, and IFN-gamma production. The impaired NK cell reactivity was not due to induction of apoptosis but mediated by down-regulation of the activating immunoreceptor Natural killer group 2, member D (NKG2D) on NK cells by platelet-derived transforming growth factor beta (TGF-beta). Neutralization of TGF-beta in platelet releasate not only prevented NKG2D down-regulation but also restored NK cell antitumor reactivity. Thus, our data elucidate the molecular basis of the previously described influence of platelets on NK cell antitumor reactivity and suggest that therapeutic intervention in tumor cell-platelet interaction and the resulting TGF-beta release by platelets may serve to enhance antitumor immunity.

J Immunol. 2009 Oct 1; 183(7): 4312-21
Prestwich RJ, Errington F, Steele LP, Ilett EJ, Morgan RS, Harrington KJ, Pandha HS, Selby PJ, Vile RG, Melcher AA

Oncolytic virotherapy may mediate antitumor effects via direct oncolysis or immune-mediated tumor regression. Although the ability of oncolytic viruses to generate adaptive antitumor immunity has been characterized, their interactions with the innate immune system are relatively unclear. Using a human in vitro system, this study investigates the innate immunological consequences of reovirus therapy and its potential to activate NK cell-mediated antitumor activity. Dendritic cells (DC) loaded with reovirus-infected human melanoma Mel888 cells (DC-MelReo), but not reovirus-infected tumor cells alone, induced IFN-gamma production within the NK cell population upon coculture with PBMC, in a cell-to-cell contact-dependent manner. DC-MelReo secreted the chemokines CCL2, 3, 4, 5, 7, 8, 11, and CXCL10; these culture supernatants induced NK cell chemotaxis. Coculture of DC-MelReo with purified NK cells induced reciprocal contact-dependent phenotypic DC maturation, while DC-MelReo elicited up-regulation of the activation marker CD69 on NK cells, in a partially contact and partially IL-12 dependent manner. Significantly, DC-MelReo induced NK cell cytotoxicity toward tumor cells by a type I IFN dependent mechanism. These data demonstrate that tumor infection by reovirus can act via DC to induce NK cell recruitment, activation, and cytotoxicity, along with reciprocal DC maturation. These findings suggest that reciprocal DC-NK cell interactions, following reovirus therapy, may play an important role in altering the immune milieu of the tumor microenvironment and mediating tumor regression.

J Immunol. 2009 Oct 1; 183(7): 4211-9
Komaru A, Ueda Y, Furuya A, Tanaka S, Yoshida K, Kato T, Kinoh H, Harada Y, Suzuki H, Inoue M, Hasegawa M, Ichikawa T, Yonemitsu Y

We recently demonstrated efficient antitumor immunity against murine tumors using dendritic cells (DCs) activated by recombinant Sendai viruses (rSeVs), and proposed a new concept, "immunostimulatory virotherapy," for cancer immunotherapy. However, there has been little information on the efficacy of this method in preventing metastatic diseases. In this study, we investigated the efficacy of vaccinating DCs activated by fusion gene-deleted nontransmissible rSeV (rSeV/dF) using a murine model of lung metastasis. Bolus and i.v. administration of DCs harboring rSeV/dF-expressing GFP without pulsation of tumor Ag (DC-rSeV/dF-GFP) 2 days before tumor inoculation showed efficient prevention against lung metastasis of c1300 neuroblastoma, but not of RM-9 prostatic cancer. We found that the timing of DC therapy was critical for the inhibition of pulmonary metastasis of RM-9, and that the optimal effect of DCs was seen 28 days before tumor inoculation. Interestingly, the antimetastatic effect was sustained for over 3 mo, even when administered DCs were already cleared from the lung and organs related to the immune system. Although NK cell activity had already declined to baseline at the time of tumor inoculation, Ab-mediated depletion studies revealed that CD4+ cells as well as the presence of, but not the activation of, NK cells were crucial to the prevention of lung metastasis. These results are the first demonstration of efficient inhibition of lung metastasis via bolus administration of virally activated DCs that was sustained and NK/CD4+ cell-dependent, and may suggest a potentially new mechanism of DC-based immunotherapy for advanced malignancies.

Mol Cancer Ther. 2009 Sep; 8(9): 2616-24
van Rhee F, Szmania SM, Dillon M, van Abbema AM, Li X, Stone MK, Garg TK, Shi J, Moreno-Bost AM, Yun R, Balasa B, Ganguly B, Chao D, Rice AG, Zhan F, Shaughnessy JD, Barlogie B, Yaccoby S, Afar DE

Monoclonal antibody (mAb) therapy for multiple myeloma, a malignancy of plasma cells, has not been clinically efficacious in part due to a lack of appropriate targets. We recently reported that the cell surface glycoprotein CS1 (CD2 subset 1, CRACC, SLAMF7, CD319) was highly and universally expressed on myeloma cells while having restricted expression in normal tissues. Elotuzumab (formerly known as HuLuc63), a humanized mAb targeting CS1, is currently in a phase I clinical trial in relapsed/refractory myeloma. In this report we investigated whether the activity of elotuzumab could be enhanced by bortezomib, a reversible proteasome inhibitor with significant activity in myeloma. We first showed that elotuzumab could induce patient-derived myeloma cell killing within the bone marrow microenvironment using a SCID-hu mouse model. We next showed that CS1 gene and cell surface protein expression persisted on myeloma patient-derived plasma cells collected after bortezomib administration. In vitro bortezomib pretreatment of myeloma targets significantly enhanced elotuzumab-mediated antibody-dependent cell-mediated cytotoxicity, both for OPM2 myeloma cells using Natural killer or peripheral blood mononuclear cells from healthy donors and for primary myeloma cells using autologous Natural killer effector cells. In an OPM2 myeloma xenograft model, elotuzumab in combination with bortezomib exhibited significantly enhanced in vivo antitumor activity. These findings provide the rationale for a clinical trial combining elotuzumab and bortezomib, which will test the hypothesis that combining both drugs would result in enhanced immune lysis of myeloma by elotuzumab and direct targeting of myeloma by bortezomib.

Immunol cell Biol. 2009 Nov-Dec; 87(8): 579-89
Guo H, Kumar P, Moran TM, Garcia-Sastre A, Zhou Y, Malarkannan S

Natural killer (NK) cells have a critical role in clearing influenza virus, which primarily infects the lung epithelial cells. However, the ability of influenza virus to infect and manipulate NK cells has not been studied. In this context, we hypothesized that influenza virus can target NK cells leading to a functional impairment in their ability to mediate cytotoxicity and cytokine/chemokine generations. Here, we show influenza virus, PR8, can enter and infect NK cells. This infection did not alter the expression levels of activating, inhibitory or developmental receptors of NK cells. However, infection of NK cells by PR8 reduced the cytotoxicity to tumor cells that represent 'induced-self' and 'missing-self'. PR8-infection also significantly downregulated the NCR1, NKG2D, Nkpr1c, Ly49D and CD244 receptors-mediated generation of pro-inflammatory cytokines and chemokines. Mutations in the non-structural protein 1 (NS1) of influenza virus further augmented the functional impairment of NK cells. Our observations show the presence of a new, but yet to be explored, mechanism by which the influenza virus can evade immune detection.

Ann Fr Anesth Reanim. 2009 Sep; 28(9): 751-68
Forget P, De Kock M

OBJECTIVE: The Natural killer cells (NK) are an important part of non-specific cellular-mediated and antitumoral immunity. The goal of this review is to recapitulate data published over NK activity during the perioperative period and the influence of anaesthesia, analgesia and modulation of sympathetic system. DATA SOURCES: Pubmed/Medline database. STUDY SELECTION AND DATA EXTRACTION: Keywords-based selection, without limit of date: fundamental studies, randomized controlled trials and non-randomized comparative studies. DATA SYNTHESIS: In human as in animal studies, an important correlation exists between NK activity and prognosis linked to the development of metastasis. The great depression of this cytotoxicity during the perioperative period could be able to compromise host defenses. The influence of anaesthetics and analgesics is important. The effects of the opioids, the agonists and the antagonists of the sympathetic nervous system, the prostaglandins, the NSAIDs, the ketamine, the hypnotics and the locoregional anaesthesia are systematically reviewed. The limits of experimental model presented are covered. CONCLUSION: The effects of anaesthetic/analgesic drugs and techniques, the consequences of sympathomodulation on NK activity are numerous and sometimes opposite. It is important for the anaesthesiologist to keep in mind that the long term consequences of his techniques on the patients' outcome must be clarified.

Arthritis Rheum. 2009 Sep; 60(9): 2782-93
de Jager W, Vastert SJ, Beekman JM, Wulffraat NM, Kuis W, Coffer PJ, Prakken BJ

OBJECTIVE: Systemic-onset juvenile idiopathic arthritis (JIA) is an autoimmune disease characterized by arthritis and systemic features. Its pathogenesis is still largely unknown. It is characterized immunologically by Natural killer (NK) cell dysfunction and cytokine signatures that predominantly feature interleukin-1 (IL-1), IL-6, and IL-18. Since IL-18 can drive NK cell function, we examined how the high plasma levels of this cytokine are related to the documented NK cell failure in these patients. METHODS: The phenotype and function of NK cells from 10 healthy control subjects, 15 patients with polyarticular JIA, and 15 patients with systemic-onset JIA were characterized by staining and functional assays in vitro. IL-18 ligand binding was visualized by fluorescence microscopy. Phosphorylation of several MAP kinases and the IL-18 receptor beta (IL-18Rbeta) were visualized by Western blotting. RESULTS: IL-18 from the plasma of systemic-onset JIA patients stimulated the activation of NK cells from healthy controls and bound its cognate receptor. However, NK cells from systemic-onset JIA patients failed to up-regulate cell-mediated killing molecules, such as perforin and interferon-gamma, after IL-18 stimulation. Furthermore, treatment with IL-18 did not induce the phosphorylation of receptor-activated MAP kinases in NK cells. Alternate activation of NK cells by IL-12 induced NK cell cytotoxicity. We observed no additive effect of IL-18 in combination with IL-12 in systemic-onset JIA patients. Immunoprecipitation of IL-18Rbeta showed that NK cells from systemic-onset JIA could not phosphorylate this receptor after IL-18 stimulation. CONCLUSION: The mechanism of the impaired NK cell function in systemic-onset JIA involves a defect in IL-18Rbeta phosphorylation. This observation has major implications for the understanding and, ultimately, the treatment of systemic-onset JIA.