Project description:In order to better understand the factors that regulate B cell differentiation upon exposure to antigen, we compares global gene expression profiles from naive B cells with antigen-specific plasma, germinal center, and memory B cells after immunization with the T-dependent antigen, NP-CGG. The memory B cell-enriched transcripts were then compared with memory T cell-enriched and hematopoietic stem cell-enriched transcripts in order to generate a transcriptional profile of self-renewal within the hematopoietic system. Keywords: Cell Type Comparison
Project description:Adaptive features of natural killer (NK) cells have been reported in various species with different underlying mechanisms. It is unclear, however, which NK cell populations are capable of mounting antigen-specific recall responses, and how such functions are regulated at the molecular level. Here we identify and characterize a discrete population of CD49a+CD16- NK cells in the human liver that display increased epigenetic potential to elicit memory responses and has the functional properties to exert antigen-specific immunity on the skin as an effector site. Integrated chromatin-based epigenetic and transcriptomic profiling revealed unique characteristics of hepatic CD49a+CD16- NK cells when compared to conventional CD49a-CD16+ NK cells thereby defining active genomic regions and molecules underpinning distinct NK cell reactivity. In contrast to conventional NK cells, our results suggest adaptive CD49a+CD16- NK cells to be able to bypass the KIR receptor-ligand system upon antigen-specific stimulation. Furthermore, these cells were highly migratory towards chemokine gradients expressed in epicutaneous patch test lesions as an effector site of adaptive immune responses of the skin. These results define pathways operative in human antigen-specific memory NK cells and provide a roadmap for harnessing this NK cell subset for specific therapeutic or prophylactic vaccine strategies.
Project description:The purpose of this study were to test the feasibility of using pMan-antigen therapy to induce humoral tolerance. We used OVA as a model protein along with TCR transgenic OT-I and OT-II to study antigen-specific CD4+ T cell phenotypes and transcriptomic responses using RNA-seq readouts.
Project description:The immune system generates pathogen-tailored responses. The precise innate immune cell types and pathways that direct robust adaptive immune responses have not been fully characterized. By using fluorescent pathogens combined with massively parallel single cell RNA-seq, we comprehensively characterized the initial 48 hours of the innate immune response to diverse pathogens. We found that across all pathogens tested, most of the lymph node cell types and states showed little pathogen-specificity. In contrast, the rare antigen-positive cells displayed pathogen-specific transcriptional programs as early as 24 hours after immunization. In addition, mycobacteria activated a specific NK driven IFNγ response. Depletion of NK cells and IFNγ showed that IFNγ initiated a monocyte specific signaling cascade, leading to production of major chemokines and cytokines that promote Th1 development. Our systems immunology approach sheds light on early events in innate immune responses and may help further development of safe and efficient vaccines.
Project description:Induction of adaptive immune responses to commensal microbes is critical for intestinal homeostasis, and perturbation of these responses is associated with multiple chronic inflammatory disorders. However, the mechanisms underlying the induction and regulation of mucosal B cells targeting commensal microbes remain poorly understood, in part due to a lack of tools to identify commensal-specific B cells ex vivo. To address this, we first sought to identify immunodominant protein epitopes recognized by Segmented Filamentous Bacteria (SFB) specific serum antibodies using a whole-genome phage display screen and identified immunogenic proteins engaging IgA, IgG1 and IgG2b responses. Using these antigens, we generated B cell tetramers to identify and track SFB-specific B cell responses in the gut associated lymphoid tissue during natural and de novo colonization. We identified a compartmentalized response in B cell activation between Peyer’s patches and mesenteric lymph nodes, with a gradient of IgA, IgG1 and IgG2b isotypes along the small intestine, and selective production of IgG2b with the mesenteric lymph node chain. VDJ sequencing analyses and generation of SFB-specific monoclonal antibodies identified that somatic hypermutation drives affinity maturation to SFB derived antigens under homeostatic conditions. By combining phage display screening and B cell tetramer technologies, we now enable antigen-level based studies of immunity to intestinal microbes, which will advance our understanding of the ontogeny and function of commensal-specific B cell responses in tissue immunity, inflammation and repair.