Ursula Bommhardt

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Cellular decisions are determined by complex molecular interaction networks. Large-scale signaling networks are currently being reconstructed, but the kinetic parameters and quantitative data that would allow for dynamic modeling are still scarce. Therefore, computational studies based upon the structure of these networks are of great interest. Here, a(More)
Surface-contact-mediated signaling induced by the measles virus (MV) fusion and hemagglutinin glycoproteins is necessary and sufficient to induce T-cell unresponsiveness in vitro and in vivo. To define the intracellular pathways involved, we analyzed interleukin (IL)-2R signaling in primary human T cells and in Kit-225 cells. Unlike IL-2-dependent(More)
Sepsis induces extensive death of lymphocytes that may contribute to the immunosuppression and mortality of the disorder. The serine/threonine kinase Akt is a key regulator of cell proliferation and death. The purpose of this study was to determine whether overexpression of Akt would prevent lymphocyte apoptosis and improve survival in sepsis. In addition,(More)
T cell maturation requires the rearrangement of clonotypic T cell receptors (TCR) capable of interacting with major histocompatibility complex (MHC) ligands to initiate positive and negative selection. Only 3-5% of thymocytes mature to join the peripheral T cell pool. To investigate the basis for this low success rate, we have measured the frequency of(More)
Mouse spleen contains CD4+, CD8alpha+, and CD4-/CD8alpha- dendritic cells (DCs) in a 2:1:1 ratio. An analysis of 70 surface and cytoplasmic antigens revealed several differences in antigen expression between the 3 subsets. Notably, the Birbeck granule-associated Langerin antigen, as well as CD103 (the mouse homologue of the rat DC marker OX62), were(More)
The thymus is central to the establishment of a functioning immune system. Here is the place where T cells mature from hematopoietic progenitors, driven by mutual interactions of stromal cells and the developing thymocytes. As a result, different types of T cells are generated, all of which have been carefully selected for the ability to act in host defense(More)
Interleukin 7 (IL-7) has a critical role in the development of early CD4(-)CD8(-) double-negative (DN) thymocytes. Although the transcription factor STAT5 is an important component of IL-7 signaling, differences in the phenotypes of mice deficient in STAT5, IL-7, IL-7 receptor alpha (IL-7rα) or the kinase Jak3 suggest the existence of STAT5-independent IL-7(More)
We have investigated the role of the mitogen-activated protein kinase (MAPK) pathway in the differentiation of CD4+ and CD8+ T cells by looking specifically at the effects of inhibitors of MAPK-activating enzyme, MAPK/extracellular signal-related kinase (ERK) kinase (MEK), during the positive selection step from double-positive to single-positive (SP)(More)
NF-ATp and NF-ATc are the most prominent nuclear NF-AT transcription factors in peripheral T lymphocytes. After T cell activation both factors bind to and control the promoters and enhancers of numerous lymphokine and receptor ligand genes. In order to define a specific role for NF-ATp in vivo we have inactivated the NF-ATp gene by gene targeting in mice.(More)
In the past, ZAP70 was considered a T cell-specific kinase, and its aberrant expression in B-CLL cells was interpreted as a sign of malignant transformation and dedifferentiation. It was only recently that ZAP70 was detected in normal human B cells. In this study, we show that TLR9-activated B cells resemble B-cell chronic lymphocytic leukemia cells with(More)