Plasmodium-specific atypical memory B cells are short-lived activated B cells

A subset of atypical memory B cells accumulates in malaria and several infections, autoimmune disorders and aging in both humans and mice. It has been suggested these cells are exhausted long-lived memory B cells, and their accumulation may contribute to poor acquisition of long-lasting immunity to certain chronic infections, such as malaria and HIV. Here, we generated an immunoglobulin heavy chain knock-in mouse with a BCR that recognizes MSP1 of the rodent malaria parasite, Plasmodium chabaudi. In combination with a mosquito-initiated P. chabaudi infection, we show that Plasmodium-specific atypical memory B cells are short-lived and disappear upon natural resolution of chronic infection. These cells show features of activation, proliferation, DNA replication, and plasmablasts. Our data demonstrate that Plasmodium-specific atypical memory B cells are not a subset of long-lived memory B cells, but rather short-lived activated cells, and part of a physiologic ongoing B-cell response

Interplay of IL-4, IL-21, and ifnγ on memory B cell fate decisions

The ability to establish a durable pool of memory B (BMEM) cells is not only a key feature of adaptive immunity but also critical for host survival upon secondary infection. Depending on the nature of the pathogen, preimmune B cells differentiate into various BMEM cells associated with a particular immunoglobulin isotype. Moreover, cytokines dictate this process via the induction of transcription factors resulting in a stable lineage. Recently, the transcription factor, T-BET, has been implicated in reinforcing BMEM cells of the IgG 2c isotype. Further, phenotypically similar cells express the integrin, CD11c, and appear in humoral autoimmunity and aged mice. However, the activation requisites and extrinsic cues driving T-BET and CD11c expression remain poorly defined. T follicular helper (TFH) cells instruct B cells to adopt various BMEM cell fates via the production of cytokines—specifically IL-4, IL-21 and IFNγ. Here we reveal a novel interplay among these cytokines in determining T-BET+ B cell fate. We find that IL-21 or IFNγ directly promote T-BET+ B cells in the context of TLR engagement. Further, IL-4 antagonizes IL-21-induced T-BET expression, but augments that of IFNγ. Finally, IL-21, but not IFNγ, promotes CD11c expression. Using well-defined infections that drive IL-21 and robust IFNγ or IL-4 production, we show that these same cytokine interactions function in vivo to determine T-BET and CD11c expression. We elaborate a model in which abundant IFNγ will drive T-BET+ B cells; however, in the absence of IFNγ, IL-21 and IL-4 reciprocally regulate both T-BET and CD11c. Importantly, CD11c expression is restricted to BMEM cells, which phenotypically resemble Age-associated B cells (ABCs). In accord with our infection results, we show that T-BET +CD11c+ ABCs are likely a pool BMEM cells. Consistent with this idea, ABCs are somatically mutated, class-switched, and require the ability to present antigen and receive costimulation to form. These findings suggest that T-BET+ B cells seen in health and autoimmunity share the common initiating features of TLR driven activation within this circumscribed cytokine milieu

Evaluation and alignment of Ronchi phase gratings in the lateral shearing interferometer at 193nm wavelength

Thesis (M.S.)--University of Rochester. Institute of Optics, 2004. Missing page vi.The Lateral Shearing Interferometer (LSI) with two Ronchi phase gratings is an ideal tool to measure optical systems at deep ultraviolet (DUV) light. The geometry and construction of the LSI circumvent the tight constraints needed in conventional dual path interferometers, such as the Twyman-Green interferometer and others. Light sources at DUV have short temporal coherence lengths, thus hindering conventional interferometers from operating at DUV light. This constraint is eliminated by the geometry of the LSI, since it exploits the spatial coherence properties of the DUV light sources. The LSI offers many benefits over dual path interferometers because the LSI is self referencing, compact, and resilient to mechanical vibrations. Other factors like matching the intensity, the polarization, and the dispersion of DUV light do not interfere with the ability of the LSI to measure the wavefront, unlike in the conventional dual path interferometers. This makes the LSI a superior interferometer to be used with DUV light over the other systems. The thesis deals with the theory, the choice of materials, the tolerance of Ronchi phase gratings, and the construction and alignment of the LSI at 193nm wavelength. The evaluation of the optical properties of the Ronchi phase gratings and their mechanical alignment in the LSI is the primary focus of this thesis. If the optical properties of the gratings are not quantified and the mechanical alignment of the gratings is not precisely executed, the LSI will not be operational. From the evaluation of the data obtained from the gratings and the modeling of the mechanical alignment of the gratings, the resolution of the LSI was calculated to be λ/25 at 193nm wavelength

Transcription factor zinc finger and BTB domain 1 is essential for lymphocyte development.

Absent T lymphocytes were unexpectedly found in homozygotes of a transgenic mouse from an unrelated project. T cell development did not progress beyond double-negative stage 1 thymocytes, resulting in a hypocellular, vestigial thymus. B cells were present, but NK cell number and B cell isotype switching were reduced. Transplantation of wild-type hematopoietic cells corrected the defect, which was traced to a deletion involving five contiguous genes at the transgene insertion site on chromosome 12C3. Complementation using bacterial artificial chromosome transgenesis implicated zinc finger BTB-POZ domain protein 1 (Zbtb1) in the immunodeficiency, confirming its role in T cell development and suggesting involvement in B and NK cell differentiation. Targeted disruption of Zbtb1 recapitulated the T(-)B(+)NK(-) SCID phenotype of the original transgenic animal. Knockouts for Zbtb1 had expanded populations of bone marrow hematopoietic stem cells and also multipotent and early lymphoid lineages, suggesting a differentiation bottleneck for common lymphoid progenitors. Expression of mRNA encoding Zbtb1, a predicted transcription repressor, was greatest in hematopoietic stem cells, thymocytes, and pre-B cells, highlighting its essential role in lymphoid development

Neoantigen-specific stem cell memory-like CD4+ T cells mediate CD8+ T cell-dependent immunotherapy of MHC class II-negative solid tumors.

CD4+ T cells play key roles in a range of immune responses, either as direct effectors or through accessory cells, including CD8+ T lymphocytes. In cancer, neoantigen (NeoAg)-specific CD8+ T cells capable of direct tumor recognition have been extensively studied, whereas the role of NeoAg-specific CD4+ T cells is less well understood. We have characterized the murine CD4+ T cell response against a validated NeoAg (CLTCH129>Q) expressed by the MHC-II-deficient squamous cell carcinoma tumor model (SCC VII) at the level of single T cell receptor (TCR) clonotypes and in the setting of adoptive immunotherapy. We find that the natural CLTCH129>Q-specific repertoire is diverse and contains TCRs with distinct avidities as measured by tetramer-binding assays and CD4 dependence. Despite these differences, CD4+ T cells expressing high or moderate avidity TCRs undergo comparable in vivo proliferation to cross-presented antigen from growing tumors and drive similar levels of therapeutic immunity that is dependent on CD8+ T cells and CD40L signaling. Adoptive cellular therapy (ACT) with NeoAg-specific CD4+ T cells is most effective when TCR-engineered cells are differentiated ex vivo with IL-7 and IL-15 rather than IL-2 and this was associated with both increased expansion as well as the acquisition and stable maintenance of a T stem cell memory (TSCM)-like phenotype in tumor-draining lymph nodes (tdLNs). ACT with TSCM-like CD4+ T cells results in lower PD-1 expression by CD8+ T cells in the tumor microenvironment and an increased frequency of PD-1+CD8+ T cells in tdLNs. These findings illuminate the role of NeoAg-specific CD4+ T cells in mediating antitumor immunity via providing help to CD8+ T cells and highlight their therapeutic potential in ACT

Transcription factor zinc finger and BTB domain 1 is essential for lymphocyte development.

Absent T lymphocytes were unexpectedly found in homozygotes of a transgenic mouse from an unrelated project. T cell development did not progress beyond double-negative stage 1 thymocytes, resulting in a hypocellular, vestigial thymus. B cells were present, but NK cell number and B cell isotype switching were reduced. Transplantation of wild-type hematopoietic cells corrected the defect, which was traced to a deletion involving five contiguous genes at the transgene insertion site on chromosome 12C3. Complementation using bacterial artificial chromosome transgenesis implicated zinc finger BTB-POZ domain protein 1 (Zbtb1) in the immunodeficiency, confirming its role in T cell development and suggesting involvement in B and NK cell differentiation. Targeted disruption of Zbtb1 recapitulated the T(-)B(+)NK(-) SCID phenotype of the original transgenic animal. Knockouts for Zbtb1 had expanded populations of bone marrow hematopoietic stem cells and also multipotent and early lymphoid lineages, suggesting a differentiation bottleneck for common lymphoid progenitors. Expression of mRNA encoding Zbtb1, a predicted transcription repressor, was greatest in hematopoietic stem cells, thymocytes, and pre-B cells, highlighting its essential role in lymphoid development

Growth and Characterization of Graphene Layers on Different Kinds of Copper Surfaces

Graphene films were grown by chemical vapor deposition on Cu foil. The obtained samples were characterized by Raman spectroscopy, ellipsometry, X-ray photoelectron spectroscopy and electron back-scatter diffraction. We discuss the time-dependent changes in the samples, estimate the thickness of emerging Cu2O beneath the graphene and check the orientation-dependent affinity to oxidation of distinct Cu grains, which also governs the manner in which the initial strong Cu-graphene coupling and strain in the graphene lattice is released. Effects of electropolishing on the quality and the Raman response of the grown graphene layers are studied by microtexture polarization analysis. The obtained data are compared with the Raman signal of graphene after transfer on glass substrate revealing the complex interaction of graphene with the Cu substrate