O sistema NADPH oxidase é um complexo enzimático gerador de superóxido. O NF-kB é um fator de transcrição envolvido no controle da expressão de diversos genes ligados à resposta inflamatória. Defeitos no eixo IL-12/23-IFN-g resultam em infecções recorrentes e à susceptibilidade mendeliana a micobacterioses, podendo diminuir a expressão do componente gp91-phox da NADPH oxidase. Estudamos qual é a relação direta do NF-kB e de defeitos no eixo IL-12/23-IFN-g na regulação dos genes CYBA, NCF1, NCF2 e NCF4 do sistema NADPH oxidase humano em células U937, células B EBV transformadas provenientes de pacientes com EDA-ID, DGC, ou de pacientes com defeitos no eixo IL-12/23-IFN-g. A expressão dos genes NCF1 e NCF2 foi diminuída em células com defeitos no eixo (IFNGR1 e INFGR2) e em células U937 IkB S32A/S36A. A expressão do gene NCF1 também foi diminuída em células EDA-ID S32I e em células EDA-ID NEMO/IKKg W420X. O NF-kB e os IFNGR1 e INFGR2 são necessários para a expressão dos genes NCF1 e NCF2 e para a ativação do sistema NADPH oxidase humano neste sistema modelo. / The NADPH oxidase system is an enzymatic complex that generates superoxide. The NF-kB is a transcriptional factor involved in the expression of several genes related to the inflammatory response. The IL-12/23-IFN-g axis defects lead to recurrent infections and to the mendelian susceptibility of mycobacterial disease (MSMD), and they can decrease the gp91-phox expression (a NADPH oxidase component). We studied the NF-kB and the IL-12/23-IFN-g axis defects consequences on the regulation of CYBA, NCF1, NCF2 and NCF4 genes of the human NADPH oxidase system in U937 cells, and in B EBV cells from patients with EDA-ID, DGC, or patients with IL-12/23-IFN-g axis defects. The NCF1 and NCF2 gene expression was decreased in IL-12/23-IFN-g axis defects cells (IFNGR1 and INFGR2) and in U937 IkB S32A/S36A cells. NCF1 gene expression was decreased in EDA-ID S32I and in EDA-ID NEMO/IKKg W420X cell lineages. The NF-kB and the IFNGR1 and INFGR2 are necessary for NCF1 and NCF2 gene expression and activation of the human NADPH oxidase in this model system.

IL-12 family cytokines IL-23 and IL-27 play an important role linking innate and adaptive immunity, and regulating T-cell responses. The production of IL-12, a structurally similar cytokine, is decreased in chronic HIV infection; therefore IL-23 and IL-27 may also be influenced by HIV infection. I hypothesized that HIV inhibits LPS-induced IL-23 and IL-27 production in human MDMs by suppressing the activation of signalling pathways regulating their expression. In vitro HIV-infection of MDMs did not have any effect on basal secretion of IL-23 or IL-27; however, HIV inhibited LPS-induced production of IL-12/23 p40 and IL-23 p19, and IL-27 EBI3 and IL-27 p28 mRNA expression, and IL-23, IL-12/23 p40 and IL-27 secretion. In order to evaluate the molecular mechanisms by which HIV inhibits IL-23 and IL-27 in LPS-stimulated MDMs, the signalling pathways regulating their expression were evaluated. The PI3K, p38 MAPK, and JNK MAPK pathways were found to positively regulate LPS-induced IL-27 secretion. Interestingly, in vitro HIV infection inhibited LPS-induced p38 and JNK MAPK activation in MDMs. In summary, I have shown that HIV inhibits IL-23 and IL-27 production in LPS-stimulated MDMs and that HIV may inhibit LPS-induced IL-27 production through the inhibition of p38 and JNK MAPK activation. It is currently unknown whether PKCs regulate LPS-induced IL-23 or IL-27 in human monocytes/macrophages. I demonstrated that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 secretion within THP-1 cells, primary monocytes, and MDMs. Classical PKCs were found to positively regulate LPS-induced IL-12/23 p40 and IL-27 p28 mRNA expression and IL-12/23 p40, IL-23, and IL-27 secretion in primary human monocytes. Similarly, the classical PKCs were found to positively regulate IL-27 p28 mRNA expression and IL-27 secretion in THP-1 cells. However, classical PKCs did not regulate LPS-induced IL-27 production in MDMs, or LPS-induced IL-23 production in THP-1 cells. Overall, this demonstrates that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 production in different myeloid cells.

IL-12 family cytokines IL-23 and IL-27 play an important role linking innate and adaptive immunity, and regulating T-cell responses. The production of IL-12, a structurally similar cytokine, is decreased in chronic HIV infection; therefore IL-23 and IL-27 may also be influenced by HIV infection. I hypothesized that HIV inhibits LPS-induced IL-23 and IL-27 production in human MDMs by suppressing the activation of signalling pathways regulating their expression. In vitro HIV-infection of MDMs did not have any effect on basal secretion of IL-23 or IL-27; however, HIV inhibited LPS-induced production of IL-12/23 p40 and IL-23 p19, and IL-27 EBI3 and IL-27 p28 mRNA expression, and IL-23, IL-12/23 p40 and IL-27 secretion. In order to evaluate the molecular mechanisms by which HIV inhibits IL-23 and IL-27 in LPS-stimulated MDMs, the signalling pathways regulating their expression were evaluated. The PI3K, p38 MAPK, and JNK MAPK pathways were found to positively regulate LPS-induced IL-27 secretion. Interestingly, in vitro HIV infection inhibited LPS-induced p38 and JNK MAPK activation in MDMs. In summary, I have shown that HIV inhibits IL-23 and IL-27 production in LPS-stimulated MDMs and that HIV may inhibit LPS-induced IL-27 production through the inhibition of p38 and JNK MAPK activation. It is currently unknown whether PKCs regulate LPS-induced IL-23 or IL-27 in human monocytes/macrophages. I demonstrated that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 secretion within THP-1 cells, primary monocytes, and MDMs. Classical PKCs were found to positively regulate LPS-induced IL-12/23 p40 and IL-27 p28 mRNA expression and IL-12/23 p40, IL-23, and IL-27 secretion in primary human monocytes. Similarly, the classical PKCs were found to positively regulate IL-27 p28 mRNA expression and IL-27 secretion in THP-1 cells. However, classical PKCs did not regulate LPS-induced IL-27 production in MDMs, or LPS-induced IL-23 production in THP-1 cells. Overall, this demonstrates that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 production in different myeloid cells.

L'axe IL-12-IFN-γ joue un rôle important dans l'immunité anti-mycobactérienne. J'ai identifié et étudié une cohorte de 137 patients présentant un déficit autosomique récessif complet d'IL12RB1 qui code la sous-unité β1 des récepteurs de l'IL-12 et de l'IL-23. Ces patients sont issus de 101 familles provenant de 30 pays. Ils présentent une grande diversité génétique avec 52 allèles mutants différents. Le phénotype cellulaire avec un défaut complet de réponse à l'IL-12 est homogène chez tous les patients. Les phénotypes cliniques sont eux très hétérogènes allant de l'absence d'infection jusqu'au décès. Il s'agit en grande majorité d'infections mycobactériennes (BCG, mycobactéries environnementales et tuberculose) et/ou à salmonelles. La candidose est aussi retrouvée associée à ce défaut chez un grand nombre de patients. L'axe IL-23-IL-17 participe à la différentiation et à l'activation des lymphocytes T CD4+ dits de type Th17. les cytokines et les mécanismes contrôlant la différentiation de ces cellules sont peu connus. J'ai étudié le développement des lymphocytes producteurs d'IL-17 chez des patients porteurs de défauts génétiques affectant la voie du TGF-β (patients TGFBR1, TGFBR2 et TGFB1), de l'IL-1β (patients IRAK4 et MYD88), de l'IL-6 (patients STAT3) et de l'IL-23 (patients IL12B et IL12RB1). Pour cela, j'ai quantifié la production et la sécrétion d'IL-17 dans deux modèles expérimentaux ex vivo et in vitro. Les patients IL12B-/- et IL12RB1-/-, et de façon plus drastique les patients STAT3-/- présentent une diminution des lymphocytes producteurs d'IL-17, ce qui suggère l'importance de ces molécules dans la différentiation et l'expansion des cellules Th17 in vivo

Interleukin-12 (IL-12) ist ein zentrales Zytokin in der Entwicklung einer protektiven, zellulären Typ 1-Immunantwort. Es ist aus einer p40- und einer p35-Untereinheit aufgebaut. Es stimuliert NK- und T-Zellen zur Ausschüttung großer Mengen IFN-gamma und setzt so eine Typ 1-Immunantwort in Gang. Die p40-Untereinheit des IL-12 kommt auch in anderen biologisch wirksamen Verbindungen wie beispielsweise als Monomer, Homodimer oder als IL-23 (in Verbindung mit einer p19-Untereinheit) vor. Während das Homodimer in der vorliegenden Arbeit als reiner Antagonist zu IL-12 zu wirken scheint, wurden für IL-23 bereits zu IL-12 agonistische Wirkungen demonstriert. Im Mittelpunkt der vorliegenden Arbeit stand die Erarbeitung p40-abhängiger Wirkungen unter Ausschluß der Effekte von IL-12, d. h. möglicherweise IL-23-abhängiger Effekte. In den vorliegenden Untersuchungen wurde mit gendeletierten Mäusen gearbeitet, so dass IL-12 in diesen Systemen keine Rolle spielen kann sondern nur die p40-Proteine außer IL-12. Im Infektionsmodell mit Salmonella Enteritidis wurden p35-gendeletierte (p35-/--) und p40-/--Mäuse verwendet. Durch eine Induktion der p40-Expression waren Unterschiede auf die Wirkung der p40-Proteine zurückzuführen. Es zeigte sich, dass p40-Proteine durch die Induktion einer IFN-gamma Produktion eine Verbesserung der Abtötung intrazellulärer Pathogene bewirkten. Dadurch gelang in den p35-/--Mäusen die Eindämmung der systemischen Infektion besser und diese Mäuse überlebten länger als die p40-/--Mäuse. In Tumormodellen mit dem Lewis-Lungenkarzinom und dem Melanom B16 wurden p35/40-/--Mäuse, welche keine p40-Proteine bilden können, mit der für p40 kodierenden DNA gentherapiert. Durch diese lokale Gentherapie kam es zu einer Reduktion des Tumorwachstums. In immunhistologischen Untersuchungen war eine Rekrutierung von Makrophagen und eine Hemmung der Angiogenese im Tumorbereich sichtbar. Lokale und systemische Proteintherapien mit dem Homodimer oder IL-23 hatten keinen Effekt auf das Wachstum des Tumors, was auf die Existenz eines weiteren noch unbekannten heterodimeren p40-Proteins hindeutet. In vitro konnte gezeigt werden, dass IL-23 die IFN-gamma-Produktion durch Splenozyten induziert und dieser Effekt durch das Homodimer antagonisiert werden kann. Interessanterweise kann es in primären Milzzellkulturen auch IL-12 antagonisieren. Eine In-vitro-Infektion führte zu einer p40-abhängigen IFN-gamma-Produktion, die auch durch das Homodimer antagonisiert werden konnte. Während die Effekte der p40-Proteine im Infektionsmodell möglicherweise auf IL-23 zurückgeführt werden können und diese Effekte auch durch In-vitro-Untersuchungen gestützt werden, muss nach den Ergebnissen im Tumormodell auf die Existenz eines weiteren, bisher unbekannten p40-Proteines, p40-x, geschlossen werden. / Interleukin-12 (IL-12) is a key cytokine in the development of a protective cellular Th1 immune response. It consists of a p40 and a p35 subunit. Following stimulation with IL-12, NK and T cells produce large amounts of IFN-gamma resulting in a type 1 immune response. The p40 subunit of IL-12 is also part of other biologically active proteins such as monomeric or homodimeric p40 or the heterodimeric IL-23 (in combination with a p19 subunit). While in this study the homodimeric p40 appears to antagonize IL-12, IL-23 was demonstrated to have agonistic effects. The aim of this study was to investigate p40-dependent effects which can be observed independently of IL-12, i.e. potential effects mediated by IL-23. For the experiments mutant mice were used so that IL-12 dependent mechanisms could not play a role but only p40-dependent proteins excluding IL-12. In a Salmonella Enteritidis infection model p35-gene deleted (p35-/-) and p40-/- mice were used. As the expression of p40 is induced by bacterial antigen, differences between the strains were caused by the p40 protein. During the infection p40 proteins induced IFN-gamma production thus improving the killing of intracellular pathogens. This resulted in a better control of the systemic infection and longer survival periods of the p35-/- mice as compared to p40-/- mice. For the experiments in the tumor model using the Lewis-Lung carcinoma and the Melanoma B16 as tumors, p35/40-/- mice which are unable to produce any p40 proteins, received gene therapy with DNA encoding for p40. This local gene therapy resulted in a reduced tumor growth. Immunohistochemical examination revealed an infiltration of the tumor tissue with macrophages and a reduced neoangiogenesis within the tumor. This effect could not be achieved by local administration of IL-23 or the p40-homodimer as a protein, indicating the existence of an as yet unknown heterodimeric p40 protein. In vitro experiments showed that IL-23 induces IFN-gamma production by splenocytes and this effect can be antagonized by the homodimer. Interestingly, IL-23 is also able to antagonize IL-12 in primary splenocyte cultures. In vitro infection with Salmonella resulted in an p40-dependent IFN-gamma production that could also be antagonized by the homodimer. The protective effects in the infection model might be caused by IL-23, which is supported by the in vitro results. On the other hand, in the tumor model IL-23 does not seem to be the player and it must be concluded that the protective effects are caused by an other as yet unknown p40-dependent protein p40-x.

Mucosal associated invariant T (MAIT) cells are a population of innate-like lymphocytes, with an emerging role in tuberculosis (TB). They are characterised by the expression of high levels of CD161 and IL-18Rα, possession of a Vα7.2⁺ T cell receptor (TCR), and restriction by the MHC class I-related protein (MR1). MAIT cells can be activated by MR1 presenting microbe-derived riboflavin metabolites; or, by the cytokines IL-12 and IL-18 in a TCR-independent fashion. How human MAIT cells integrate these signals for their activation in response to Mtb is unclear. Lymphatic TB (LNTB) is a common extra-pulmonary manifestation of TB; however, little is known about the status of MAIT cells in LNTB - or in other granulomatous diseases, such as sarcoidosis. In this study, an in vitro approach was used to probe MAIT cell activation by Mtb, and the roles of IL-12/-18, the TCR, cell-cell contact and the immunological synapse (IS). Following TCR ligation, TNFα expression was rapid and transient, and was enhanced following sustained IL-12/-18 exposure. IFNγ expression occurred following sustained exposure to ng/ml concentrations of IL-12/-18; however, alongside TCR stimulation, pg/ml concentrations were sufficient. Using an artificial bilayer system, CD161 was excluded from the central regions of the MAIT cell IS, whilst the distribution of IL-18Rα remained unaffected. In response to Mtb and BCG, MR1 was necessary for rapid activation and TNFα expression, IL-12/-18 were necessary for robust and sustained IFNy expression, whilst an anti-Mtb effect was indicated in an intracellular infection model. Assessment of patients with TB or sarcoid lymphadenopathy revealed a depletion of MAIT cells in the blood in sarcoidosis, but not LNTB. In both groups, MAIT cells could be detected within a proportion of sampled lymph nodes. Overall, these findings indicate the importance of inflammatory cytokine signals in the induction of high-intensity and sustained MAIT cell effector function, including in response to Mtb. The observation of a numerical deficiency of MAIT cells in sarcoidosis requires further investigation.

IL-12 family cytokines IL-23 and IL-27 play an important role linking innate and adaptive immunity, and regulating T-cell responses. The production of IL-12, a structurally similar cytokine, is decreased in chronic HIV infection; therefore IL-23 and IL-27 may also be influenced by HIV infection. I hypothesized that HIV inhibits LPS-induced IL-23 and IL-27 production in human MDMs by suppressing the activation of signalling pathways regulating their expression. In vitro HIV-infection of MDMs did not have any effect on basal secretion of IL-23 or IL-27; however, HIV inhibited LPS-induced production of IL-12/23 p40 and IL-23 p19, and IL-27 EBI3 and IL-27 p28 mRNA expression, and IL-23, IL-12/23 p40 and IL-27 secretion. In order to evaluate the molecular mechanisms by which HIV inhibits IL-23 and IL-27 in LPS-stimulated MDMs, the signalling pathways regulating their expression were evaluated. The PI3K, p38 MAPK, and JNK MAPK pathways were found to positively regulate LPS-induced IL-27 secretion. Interestingly, in vitro HIV infection inhibited LPS-induced p38 and JNK MAPK activation in MDMs. In summary, I have shown that HIV inhibits IL-23 and IL-27 production in LPS-stimulated MDMs and that HIV may inhibit LPS-induced IL-27 production through the inhibition of p38 and JNK MAPK activation. It is currently unknown whether PKCs regulate LPS-induced IL-23 or IL-27 in human monocytes/macrophages. I demonstrated that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 secretion within THP-1 cells, primary monocytes, and MDMs. Classical PKCs were found to positively regulate LPS-induced IL-12/23 p40 and IL-27 p28 mRNA expression and IL-12/23 p40, IL-23, and IL-27 secretion in primary human monocytes. Similarly, the classical PKCs were found to positively regulate IL-27 p28 mRNA expression and IL-27 secretion in THP-1 cells. However, classical PKCs did not regulate LPS-induced IL-27 production in MDMs, or LPS-induced IL-23 production in THP-1 cells. Overall, this demonstrates that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 production in different myeloid cells.

Dentre pacientes com imunodeficiências primárias, existem aqueles com defeitos de fagócitos e outros componentes da imunidade inata. A doença granulomatosa crônica (DGC) é uma imunodeficiência primária (IDP) causada por mutações em um dos componentes protéicos, gp91-phox, p22-phox, p47-phox, p67-phox e p40-phox, da nicotinamida adenina dinucleotídeo fosfato (NADPH) dos fagócitos. Pacientes com DGC apresentam maior susceptibilidade a infecções, assim como hiperinflamação e reação adversa à vacinas como à do Bacilo Calmette-Guérin (BCG), como consequência da atividade microbicida defeituosa dos fagócitos. Por outro lado, a susceptibilidade mendeliana a micobactérias (MSMD) é uma condição que predispõe os pacientes a infecções pelo gênero Mycobacterium sp, levando a infecções graves e por vezes à morte. O objetivo deste trabalho foi realizar o diagnóstico clínico e a análise genético-molecular de pacientes brasileiros com DGC e MSMD. A explosão respiratória de granulócitos foi avaliada pelo ensaio de dihidrorodamina (DHR). A dosagem de citocinas do eixo IL-12/IFN-&#947 foi realizada mediante o ensaio de ELISA após estimulo com lisado de micobactérias (LM), proteína purifica (PPD) e BCG. O DNA genômico dos pacientes foi extraído, amplificado e sequenciado pelo método de Sanger e seqüenciamento completo de exoma. Durante o período de 2014-2018, 181 pacientes com histórico clínico sugestivo de DGC e 75 pacientes com diagnóstico sugestivo de MSMD foram encaminhados ao nosso laboratório. Após avaliação clínica e bioquímica dos pacientes, 23 deles foram diagnosticadas com DGC e 16 com MSMD. A análise genético-molecular permitiu identificar mutações em 14 pacientes com DGC, nove deles com DGC ligada ao cromossomo X (DGC-X) e 5 com DGC autossômica recessiva (DGC-AR). Identificamos mutações em 5 pacientes com MSMD, sendo três delas no receptor de IL-12 e duas no receptor da IL-17. / Among patients with primary immunodeficiencies, there are those with defects in phagocytes and other components of the innate immunity. Chronic granulomatous disease (CGD) is a primary immunodeficiency (PID) caused by mutations in one of the protein components, gp91-phox, p22-phox, p47-phox, p67-phox and p40-phox of the Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase of phagocytes. Patients with CDG are susceptible to infections, as well as hyperinflammation and adverse reactions to vaccines such as Bacilo Calmette-Guérin (BCG) as a consequence of defective phagocytes microbicidal activity. On the other hand, Mendelian susceptibility to mycobacterial diseases (MSMD) is a condition that predisposes patients to infections by the genus Mycobacterium sp , leading to serious infections and sometimes death. The main goal of this study was to perform the clinical diagnosis and genetic-molecular analysis of Brazilian patients with CDG and MSMD. The respiratory burst of granulocytes was evaluated by the dihydrorhodamine (DHR) assay. Cytokine dosing of IL-12 / IFN-&#947 axis was performed by the ELISA assay after stimulation with mycobacterium lysate (LM), purified protein (PPD) and BCG. Patients genomic DNA was extracted, amplified and sequenced by the Sanger method and whole exome sequencing. During the period of 2014 to 2018, 181 patients with a clinical history suggestive of CDG and 75 patients with a diagnosis suggestive of MSMD were referred to our laboratory. After clinical and biochemical evaluation, 23 of them were diagnosed with CDG and 16 with MSMD. Genetic-molecular analysis allowed the identification of mutations in 14 patients with CDG, of those 9 had X-linked DGC (X-CGD) and 5 had autosomal recessive CGD (AR-CGD). Mutations were identified in 5 MSMD patients, three in the IL-12 receptor and two in the IL-17 receptor.

Le syndrome de Sjögren primitif (SSp) est une maladie auto-immune (MAI) systémique ayant des caractéristiques communes avec le lupus érythémateux. Ces caractéristiques incluent des mécanismes physiopathologiques et des facteurs de predispositions génétiques. Notre équipe et d'autres groupes ont pu mettre en evidence une signature interféron (IFN) dans les glandes salivaires et les PBMCs de patients ayant un SSp. Cette découverte a permis de mettre en évidence de nouvelles voies à explorer dans la pathogénie du SLE et SSp en permettant la focalisation des recherches sur le rôle de l'immunité innée et de la voie IFN.Nous avons confirmé le rôle de 2 gènes importants dans le SSp, impliqués dans les voies des IFN. Le premier est IRF5 sur la voie IFN de type I et STAT4 sur la voie IFN de type II. Nous avons pu mettre en évidence une fonctionnalité de l'allèle à risque d'IRF5 (Polymorphisme Indel situé dans le promoteur). Concernant STAT4, son expression n'était pas altérée par le SNP associé à la maladie. Toutefois, l'ARNm de STAT4 était corrélé à l'expression des gènes IFN de type I. Les dérégulations épigénétique pourraient jouer un rôle important dans la pathogénie de nombreuses MAI, en particulier la méthylation de l'ADN qui est hautement liée à l'extinction de l'expression des gènes. Nous avons étudié la méthylation du promoteur d'IRF5 et nous n'avons pas trouvé de régulation de ce promoteur par le méthylation. Une analyse de la méthylation avec une approche globale du méthylome est en cours dans notre équipe et permettra d'identifier de gènes cibles d'une dérégulation épigénétique pouvant être impliqués dans les MAI.Nous avons essayé de comprendre la relation entre STAT4 et gènes IFN de type I. Ainsi, nous rapportons que l'IL-12 induit spécifiquement l'IFN de type I par intéraction entre deux partenaires cellulaires, les lymphocytes T CD4+ et les cellules dendritiques plasmacytoïdes. Ces résultats pourraient expliquer l'implication des polymorphismes de STAT4 dans les MAI dépendantes de l'IFN de type I. Ces résultats suggèrent également que les MAI dépendantes des IFN de type I et II ne s'opposent pas. Elles seraient seulement le Yin et le Yang d'un facteur d'activation commun, STAT4, capable d'induire les IFNs de type I et II.

S'ha establert un sistema experimental autòleg per a poder estudiar la resposta de les cèl.lules Natural Killer (NK) contra les cèl.lules dendrítiques derivades de monòcits (moDC), infectades pel Cytomegalovirus humà (HCMV). Els nostres resultats mostren que les cèl.lules NK responen contra les moDC infectades per HCMV, que presenten una expressió de les molècules MHC de classe I a superficie reduïda. Específicament, demostrem que la infecció per HCMV disminueix l'expressió en superficie d'HLA-E en les moDC, alliberant així la inhibició de les cèl.lules NK NKG2A+. Mostrem que els NKR anomenats NKp46 i DNAM-1 tenen un paper dominant en el reconeixement de les moDC infectades per HCMV i evidenciem la importància de la dinàmica dels mecanismes d'immunoevassió en la susceptibilitat a la resposta NK. Finalment, trobem que els interferons de tipus I i la IL-12 secretats en resposta a la infecció per HCMV, a més de participar en l'activació de la cèl.lula NK i en la secreció d'IFN-, inhibeixen l'expressió i la funció de NKG2D en les cèl.lules NK, com un mecanisme de regulació potencial per prevenir la reactivitat NK contra cèl.lules veïnes sanes. / Suitable experimental conditions have been established to dissect the role of NK cell receptors (NKR) and cytokines in the NK cell response against autologous human cytomegalovirus (HCMV) infected monocyte derived dendritic cells (moDC). Our results reveal that NK cells are capable of responding to HCMV infected moDC that have down-regulated surface MHC class I molecules. In particular, we prove that HCMV infection decreases surface HLA-E expression on moDC, thus releasing NKG2A+ NK cells from inhibition. We show that NKp46 and DNAM-1 NKR play a dominant role in the recognition of HCMV infected moDC and we provide evidences stressing the importance of the dynamics of viral immune evasion mechanisms in NK cell susceptibility. Finally, we find that type I interferons and IL-12 secreted in response to HCMV infection, beyond their participation in NK cell activation and IFN- secretion, transiently inhibit the expression and function of NKG2D in NK cells, thus providing a potential regulatory feedback mechanism to prevent NK cell reactivity against bystander healthy cells.