Background T cell tolerance of allergic cutaneous contact sensitivity (CS) induced in mice by high doses of reactive hapten is mediated by suppressor cells that release antigen-specific suppressive nanovesicles. Objective To determine the mechanism(s) of immune suppression mediated by the nanovesicles. Methods T cell tolerance was induced by i.v. injections of hapten conjugated to self antigens of syngeneic erythrocytes and subsequent contact immunization with the same hapten. Lymph node and spleen cells from tolerized or control donors were harvested and cultured to produce a supernatant containing suppressive nanovesicles that were isolated for testing in active and adoptive cell transfer models of CS. Results Tolerance was shown due to exosome-like nanovesicles in the supernatant of CD8+ suppressor T cells that were not Treg. Antigen specificity of the suppressive nanovesicles was conferred by a surface coat of antibody light chains, or possibly whole antibody, allowing targeted delivery of selected inhibitory miRNA-150 to CS effector T cells. Nanovesicles also inhibited CS in actively sensitized mice after systemic injection at the peak of the responses. The role of antibody and miRNA-150 was established by tolerizing either panimmunoglobulin deficient JH-/- or miRNA-150-/- mice that produced non-suppressive nanovesicles. These nanovesicles could be made suppressive by adding antigen-specific antibody light chains or miRNA-150, respectively. Conclusions This is the first example of T cell regulation via systemic transit of exosome-like nanovesicles delivering a chosen inhibitory miRNA to target effector T cells in an antigen-specific manner by a surface coating of antibody light chains.

Asf1 is an evolutionarily conserved chaperone of H3 and H4 histones that functions in replication dependent and independent chromatin assembly. Although Asf1 has been well studied in humans and yeast (members of the Opisthokonta lineage of eukaryotes), questions remain concerning its mechanism of function. To obtain additional insight into the Asf1 function we have initiated a proteomic analysis in the ciliate protozoan T. thermophila, a member of the Alveolata lineage of eukaryotes. Our results suggest that an evolutionarily conserved function of Asf1 is mediating the nuclear transport of newly synthesized histones H3 and H4.

, triggers a transcriptional program that includes the production of type I IFNs. These antiviral cytokines signal in both autocrine and paracrine fashion through the JAK-STAT pathway leading to additional transcription events involving the differential expression of many hundreds of genes. The antiviral state produced by this extensive genetic reprogramming involves a core set of genes as well as pathogenspecific components (1).The DC response to individual pathogens involves multiple signals that must be integrated to initiate an appropriate immune response. Pathogenic viruses attempt to subvert normal immune function through the expression of IFN antagonists (2, 3). For example, IFN regulatory factor (IRF) 3 activation and IFN-b expression are blocked by the NS1 protein of influenza (4). Unraveling the impact of these immune antagonists would be aided by a detailed understanding of the genetic regulatory network that operates during an uninhibited antiviral response. This knowledge is lacking because previous human studies have used viruses that interfere with the immune response (4-6). One fundamental unresolved question is to what extent the antiviral response is a single interconnected transcriptional cascade (convergent architecture) or a combination of transcriptional events operating independently in reaction to the multiple signals that arise following viral insult (parallel architecture). Newcastle disease virus (NDV) infection of human DCs provides an ideal system to define the uninhibited regulatory network (7,8). NDV is an avian virus that is able to stimulate innate immunity and DC maturation, but lacks the ability to evade the human interferon response (9). By focusing on NDV, we can accurately depict the baseline network of transcription factor (TF) interactions that underlie a broad range of immune responses. Through comparative studies, this network will enable detailed analysis of other infections and greatly improve our understanding of the control mechanisms in antiviral immunity and the myriad ways through which pathogenic viruses subvert normal immune function.Systems biology methods combined with high-throughput experimental technologies are providing new insights into virus-host interactions (10, 11). Genome-wide transcriptional profiling has suggested that the DC antiviral response is characterized by temporal waves of gene activation, which may be controlled by different combinations of transcriptional regulators (1). Potential regulators can be implicated using direct approaches, such as differential expression of the TF mRNA (1) -regulatory motifs (12, 13). These methods typically provide a static view of the network. Other computational methods have been proposed to identify TFs driving time-dependent changes in expression, but these do not explicitly account for the regulation of the TF itself (14, 15). The most common approaches are based on the hypothesis that genes sharing a similar temporal profile are regulated by common TFs (16). In mammals, a variety of posttranscriptional ...

Increased interest in the immune system's involvement in pathophysiological phenomena coupled with decreased DNA sequencing costs have led to an explosion of antibody and T cell receptor sequencing data collectively termed “adaptive immune receptor repertoire sequencing” (AIRR-seq or Rep-Seq). The AIRR Community has been actively working to standardize protocols, metadata, formats, APIs, and other guidelines to promote open and reproducible studies of the immune repertoire. In this paper, we describe the work of the AIRR Community's Data Representation Working Group to develop standardized data representations for storing and sharing annotated antibody and T cell receptor data. Our file format emphasizes ease-of-use, accessibility, scalability to large data sets, and a commitment to open and transparent science. It is composed of a tab-delimited format with a specific schema. Several popular repertoire analysis tools and data repositories already utilize this AIRR-seq data format. We hope that others will follow suit in the interest of promoting interoperable standards.

Highlights d Tetrahymena Mediator contains at least 10 conserved subunits d ChIP-seq suggests a role for Mediator in global transcription regulation d MED31 localizes to the crescent stage of meiotic prophase in MIC during development d MED31 KD results in ectopic expression of developmental genes during mitotic growth