Sigurour Ingvarsson

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Negative selection is a process by which autoreactive lymphocytes are eliminated from the developing antigen receptor repertoire. The mechanisms regulating negative selection of immature B lymphocytes in the bone marrow are poorly elucidated. Human bone marrow cells were examined in order to investigate the presence of the members of the Fas (APO-1/CD95)(More)
Interdigitating dendritic cells (IDC) represent a mature progeny of dendritic cells (DC) in vivo and are exhibiting a strong lymphocyte stimulatory potential. Because of the restricted localization to secondary lymphoid organs where decisive cellular interactions take place in the initial events of immunity, IDC regulatory function was addressed in relation(More)
The precise signaling pathways to induce a germinal center (GC) phenotype and somatic mutations in human B cells are presently not understood. Major phenotypical hallmarks of a human GC B cell are up-regulated expression of CD10 and CD95 together with a heterogeneous expression of CD77. Activation of resting human tonsillar B cells using anti-CD40 and(More)
IgE switching requires the prior induction of C epsilon germline transcripts which is mediated by the concerted binding of STAT-6 and NF kappa B to the C epsilon promoter. These transcription factors are regulated by IL-4 and CD40, respectively. However the latter can effect other signaling pathways and the present study explores the role of p38 MAPK in(More)
BACKGROUND Type 2 T-helper cells (Th2) are involved in the regulation of the humoral immune response against antigens and allergens and directly affect which isotype will be produced. The mechanism that regulates antigen-specific IgE secretion and immune deviation is still not known. OBJECTIVES To delineate mechanisms behind antigen-specific IgE secretion(More)
BACKGROUND As the incidence of allergy to different compounds increases in society, the need to understand and characterize specific IgE responses becomes obvious. Different cell culture systems have been evaluated for their ability to support such IgE secretion. METHODS One system employed human peripheral lymphocytes (PBL) from normal donors stimulated(More)
BACKGROUND Human B cells can proliferate in vitro after stimulation with anti-Ig and via the CD40 molecule. Superantigens like SEA which bind to MHC class II antigens on, e.g. B cells can polyclonally activate T cells via interaction with their TcR. The activated T cell subsequently activates the B cells to proliferation and Ig-production. OBJECTIVES To(More)
Beckwith-Wiedemann syndrome (BWS) is a generalized overgrowth condition as well as regional and organ overgrowth in newborn children. It includes an increased risk of certain embryonal tumours. The aetiology of BWS is complex as different genetic and epigenetic alterations at chromosome region 11p15.5 may occur. We report the first case of paternal(More)
Human B cells are polyclonally activated in vitro by T cells stimulated with immobilized anti-CD3 monoclonal antibodies. We have analysed the effect of CD3 ligation on the production of antigen-specific antibodies, using peripheral blood lymphocytes from tetanus toxoid vaccinated blood donors. High levels of antigen-specific antibodies were obtained after(More)
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