Untersuchung zur Normerhebung des dichotischen Diskriminationstests nach Uttenweiler und des Marburger Reimtests zur Diagnostik auditiver Wahrnehmungsstörungen bei Kindern

In der vorliegenden Studie geht es um die Beurteilung zweier Tests, die zur Diagnostik auditiver Wahrnehmungsstörung herangezogen werden. Die auditive Wahrnehmungsstörung ist ein Krankheitsbild bei dem die periphere Hörleistung in der Regel nicht beeinträchtigt ist. Dagegen sind die zentralen Verschaltungs- und Verarbeitungsprozesse des Hörens gestört oder verändert. Da sich das Krankheitsbild durch viele verschiedene Symptome äußern kann, wird in der Diagnostik eine Testbatterie aus psychologischen und audiometrischen Tests eingesetzt. Bei dieser Studie wurden zwei Tests untersucht, die folgende Teilaspekte der zentralen Hörverarbeitung testen: 1. die Lautdiskrimination im Störgeräusch mit dem Marburger Reimtest 2. die dichotische Schallverarbeitung mit dem dichotischen Diskriminationstest nach Uttenweiler Beide Tests wurden an einer Kontrollgruppe gesunder Grundschulkinder (n= 47) durchgeführt und mit den Ergebnissen von bereits als krank diagnostizierten Kindern (n= 239) verglichen. Beim Marburger Reimtest handelt es sich um ein neues computergestütztes Testverfahren, das in der vorliegenden Arbeit an einer größeren Probandengruppe auf Praktikabilität und Aussagekraft überprüft wurde. Dabei konnte ein Teil der vorher postulierten Hypothesen bestätigt werden. Der Gruppenunterschied zwischen den kranken Kindern und der gesunden Vergleichsgruppe war aber für die BILD nicht signifikant (p>0,05). Beim Vergleich der 50%igen Verständlichkeitsschwellen schnitten die kranken Kinder in allen drei untersuchten dB-Stufen etwas besser ab als die gesunden. Auch in einer neu entwickelten Auswertungsmethode konnte kein signifikanter Unterschied zwischen den Ergebnissen der beiden Gruppen gezeigt werden. Damit lässt sich die gewählte Methodik zwar dazu nutzen, den Hörgewinn durch binaurale Verarbeitung darzustellen, sie stellt aber kein geeignetes Kriterium dar, um sicher zwischen gesunden Kindern und Kindern mit einer auditiven Wahrnehmungsstörung zu unterscheiden. Der dichotische Diskriminationstest nach Uttenweiler existiert in seiner ursprünglichen Form schon seit den frühen achtziger Jahren und wurde in seinem Testablauf und seiner Bewertungsmethodik so verändert, dass eine Normwerterhebung an kranken und gesunden Kindern und ein späterer Vergleich der beiden klinischen Gruppen nötig wurde. Dabei bestätigte sich, dass der neue Durchführungs- und Bewertungsmodus einen einfacheren und schnelleren Testablauf gewährleistet. Die errechneten Mittelwerte der erreichten Testpunktzahl zeigten einen signifikanten Unterschied (p< 0,05) zwischen Patienten und gesunder Kontrollgruppe auf. Der Cut-Off-Wert konnte bei 16 Punkten bestätigt werden. Insgesamt liefert der neue Testablauf mit dem modifizierten Auswertungsmodus ein valides Ergebnis und ist für den Einsatz zur Diagnostik von auditiven Wahrnehmungsstörungen bestens geeignet

Peptide-based immunotherapy of experimental autoimmune encephalomyelitis without anaphylaxis

Administration of peptide antigens in tolerogenic form holds promise as a specific treatment for autoimmune and allergic disorders. However, experiments in rodent autoimmune models have highlighted the risk of anaphylaxis in response to systemic peptide application once the aberrant immune response is underway. Thus, mice with clinical signs of experimental autoimmune encephalomyelitis (EAE) or diabetes have been reported to suffer fatal anaphylaxis upon administration of native autoantigenic peptides. Clearly, this might represent a significant barrier to the use of synthetic peptides in the treatment of ongoing human autoimmune conditions. Here we describe the development of an altered peptide ligand (APL) engineered to prevent anaphylaxis (no antibody binding) whilst retaining the ability to silence pathogenic myelin-reactive T lymphocytes. Administration of the APL to mice with an ongoing anti-myelin immune response did not cause anaphylaxis, but led to complete protection from the subsequent induction of EAE and, when given during ongoing EAE, led to a rapid remission of clinical signs. The approach of removing antibody recognition whilst maintaining the desired functional effect (in this case T cell tolerance) may be of value in other situations in which there is a risk of triggering anaphylaxis with peptide-based drugs

A novel CD11c.DTR transgenic mouse for depletion of dendritic cells reveals their requirement for homeostatic proliferation of natural killer cells

Dendritic cells (DC) are known to support the activation of natural killer (NK) cells. However, little is known about the role for DC in NK-cell homeostasis. In order to investigate this question, a novel bacterial artificial chromosome transgenic mouse model was generated in which the diphtheria toxin receptor is expressed under the CD11c promoter. In these mice efficient DC depletion can be achieved over prolonged periods of time by multiple injections of diphtheria toxin. We show here that NK cells require DC for full acquisition of effector function in vivo in response to the bacterial-derived TLR ligand CpG. Importantly, DC were found to play an instrumental role for maintaining normal homeostasis of NK cells. This is achieved by IL-15 production by DC, which supports the homeostatic proliferation of NK cells. . There is much known about the molecular mechanisms of NK-cell functions, but the factors influencing NK-cell numbers are only beginning to be elucidated. Mature NK cells were typically thought to be a terminally differentiated population, with a very limited selfrenewal capacity. However, it was recently shown that a small percentage of NK cells actively proliferate in the steady state, resulting in a half life of the NK-cell population of about 17 days SHORT COMMUNICATION Ã These authors contributed equally to this study. Correspondence: Dr. Natalio Garbi e-mail: n. 2776 Importantly, we observe a previously unrecognized role for DC in optimal homeostatic proliferation of NK cells in lymphopenic conditions. In this process, DC-derived IL-15 appears to play an important role. Our data indicate that not only T lymphocytes, but also NK cells require DC for homeostatic proliferation. Results CD11c.DOG mice allow long-term ablation of DC in vivo without toxicity effects In order to study the effect of in vivo interaction between DC and NK cells, a system that permits long-term depletion of DC is required. The diphtheria toxin/diphtheria toxin receptor (DT/DTR) system introduced by Saito et al. Injection of 8 ng/gram body weight (gbw) DT induced depletion of DC (CD11c high MHC class II 1 ) in spleen, lymph nodes, thymus and bone marrow, albeit efficiency of depletion varied in the different organs tested The data shown in Although mice tolerated well 8 ng/gbw for prolonged periods of time, DC depletion was limited to a period of 11-12 days In order to confirm faithful expression of the BAC, we thoroughly examined CD11c expression and depletion of B cells, T cells, NK cells and NKT cells in spleens after 8 ng/gbw DT administration. The minor CD11c hi subpopulations of these cell types were effectively depleted, whereas CD11c int/lo cells were only partially depleted (Supporting Information In conclusion, the new BAC transgenic CD11c.DOG mouse model introduced here allows effective long-term depletion of CD11c 1 cells. DC are required for optimal NK-cell activation and homeostatic proliferation in vivo of NK cells. NK cells were activated by administration of the TLR-9 ligand CpG and the in vivo lytic activity determined by injection of CFSE-labelled tapasin-deficient splenocytes that served as NK targets. CpG administration in mice with a normal DC compartment lead to increased NK cytotoxicity in vivo ( The homeostasis of T cells has been well studied and found to require several factors including the presence of DC, self MHC molecules and the cytokine IL-7 for proliferation and survival ) in DC-depleted CD11c.DOG mice compared with DC-sufficient B6 mice ( DC-derived IL-15 contributes to lymphopenia-induced proliferation of NK cells The cytokine IL-15 has been reported to be crucial for activation and survival of NK cells Concluding remarks In summary, this study introduces a new BAC transgenic CD11c.DTR mouse model for prolonged in vivo depletion of DC by application of DT, without any apparent signs of toxicity. Experiments using this mouse line demonstrated a previously unrecognized role for DC in the homeostasis of NK cells, and showed that local production of IL-15 by DC is required for the maintenance of the NK-cell compartment. Thus, the present study adds an additional function to the long list of DC functions, which so far encompass antigen presentation to and activation of CD4 and CD8 T cells, deletion of T cells and induction of regulatory 1 ) NK cells were quantified 7 days after transfer into irradiated chimeras. Three mice were used in each group. The experiment was repeated three times with similar results. Ã po0.05, Student&apos;s t-test

CD11c depletion severely disrupts Th2 induction and development in vivo

Although dendritic cells (DCs) are adept initiators of CD4+ T cell responses, their fundamental importance in this regard in Th2 settings remains to be demonstrated. We have used CD11c–diphtheria toxin (DTx) receptor mice to deplete CD11c+ cells during the priming stage of the CD4+ Th2 response against the parasitic helminth Schistosoma mansoni. DTx treatment significantly depleted CD11c+ DCs from all tissues tested, with 70–80% efficacy. Even this incomplete depletion resulted in dramatically impaired CD4+ T cell production of Th2 cytokines, altering the balance of the immune response and causing a shift toward IFN-γ production. In contrast, basophil depletion using Mar-1 antibody had no measurable effect on Th2 induction in this system. These data underline the vital role that CD11c+ antigen-presenting cells can play in orchestrating Th2 development against helminth infection in vivo, a response that is ordinarily balanced so as to prevent the potentially damaging production of inflammatory cytokines

Depletion of Dendritic Cells Enhances Innate Anti-Bacterial Host Defense through Modulation of Phagocyte Homeostasis

Dendritic cells (DCs) as professional antigen-presenting cells play an important role in the initiation and modulation of the adaptive immune response. However, their role in the innate immune response against bacterial infections is not completely defined. Here we have analyzed the role of DCs and their impact on the innate anti-bacterial host defense in an experimental infection model of Yersinia enterocolitica (Ye). We used CD11c-diphtheria toxin (DT) mice to deplete DCs prior to severe infection with Ye. DC depletion significantly increased animal survival after Ye infection. The bacterial load in the spleen of DC-depleted mice was significantly lower than that of control mice throughout the infection. DC depletion was accompanied by an increase in the serum levels of CXCL1, G-CSF, IL-1α, and CCL2 and an increase in the numbers of splenic phagocytes. Functionally, splenocytes from DC-depleted mice exhibited an increased bacterial killing capacity compared to splenocytes from control mice. Cellular studies further showed that this was due to an increased production of reactive oxygen species (ROS) by neutrophils. Adoptive transfer of neutrophils from DC-depleted mice into control mice prior to Ye infection reduced the bacterial load to the level of Ye-infected DC-depleted mice, suggesting that the increased number of phagocytes with additional ROS production account for the decreased bacterial load. Furthermore, after incubation with serum from DC-depleted mice splenocytes from control mice increased their bacterial killing capacity, most likely due to enhanced ROS production by neutrophils, indicating that serum factors from DC-depleted mice account for this effect. In summary, we could show that DC depletion triggers phagocyte accumulation in the spleen and enhances their anti-bacterial killing capacity upon bacterial infection

Induced bronchus-associated lymphoid tissue serves as a general priming site for T cells and is maintained by dendritic cells

Mucosal vaccination via the respiratory tract can elicit protective immunity in animal infection models, but the underlying mechanisms are still poorly understood. We show that a single intranasal application of the replication-deficient modified vaccinia virus Ankara, which is widely used as a recombinant vaccination vector, results in prominent induction of bronchus-associated lymphoid tissue (BALT). Although initial peribronchiolar infiltrations, characterized by the presence of dendritic cells (DCs) and few lymphocytes, can be found 4 d after virus application, organized lymphoid structures with segregated B and T cell zones are first observed at day 8. After intratracheal application, in vitro–differentiated, antigen-loaded DCs rapidly migrate into preformed BALT and efficiently activate antigen-specific T cells, as revealed by two-photon microscopy. Furthermore, the lung-specific depletion of DCs in mice that express the diphtheria toxin receptor under the control of the CD11c promoter interferes with BALT maintenance. Collectively, these data identify BALT as tertiary lymphoid structures supporting the efficient priming of T cell responses directed against unrelated airborne antigens while crucially requiring DCs for its sustained presence

TLR-4 ligation of dendritic cells is sufficient to drive pathogenic T cell function in experimental autoimmune encephalomyelitis

<p>Abstract</p> <p>Background</p> <p>Experimental autoimmune encephalomyelitis (EAE) depends on the initial activation of CD4⁺ T cells responsive to myelin autoantigens. The key antigen presenting cell (APC) population that drives the activation of naïve T cells most efficiently is the dendritic cell (DC). As such, we should be able to trigger EAE by transfer of DC that can present the relevant autoantigen(s). Despite some sporadic reports, however, models of DC-driven EAE have not been widely adopted. We sought to test the feasibility of this approach and whether activation of the DC by toll-like receptor (TLR)-4 ligation was a sufficient stimulus to drive EAE.</p> <p>Findings</p> <p>Host mice were seeded with myelin basic protein (MBP)-reactive CD4+ T cells and then were injected with DC that could present the relevant MBP peptide which had been exposed to lipopolysaccharide as a TLR-4 agonist. We found that this approach induced robust clinical signs of EAE.</p> <p>Conclusions</p> <p>DC are sufficient as APC to effectively drive the differentiation of naïve myelin-responsive T cells into autoaggressive effector T cells. TLR-4-stimulation can activate the DC sufficiently to deliver the signals required to drive the pathogenic function of the T cell. These models will allow the dissection of the molecular requirements of the initial DC-T cell interaction in the lymphoid organs that ultimately leads to autoimmune pathology in the central nervous system.</p

The human syndrome of dendritic cell, monocyte, B and NK lymphoid deficiency

Human immunodeficiency syndrome with loss of DCs, monocytes, and T reg cells; preservation of Langerhans cells; associated loss of BM multilymphoid progenitors; and overproduction of Flt3 ligand