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Biomedical subjects

Ger Arkesteijn

Publications and source records attributed to Ger Arkesteijn.

4 recordsLinked to original sources
PubMed2005

Autologous stem cell transplantation for autoimmunity induces immunologic self-tolerance by reprogramming autoreactive T cells and restoring the CD4+CD25+ immune regulatory network.

Despite a rapidly accumulating clinical experience with autologous stem cell transplantation (ASCT) as a treatment for severe refractory autoimmune disease, data on the mechanisms by which ASCT induces immune tolerance are still very scarce. In this study it is shown that ASCT restores immunologic self-tolerance in juvenile idiopathic arthritis (JIA) via 2 mechanisms. First, ASCT induces a restoration of the frequency of FoxP3 expressing CD4+CD25bright regulatory T cells (Tregs) from severely reduced numbers before ASCT to normal levels after ASCT. This recovery is due to a preferential homeostatic expansion of CD4+CD25+ Tregs during the lymphopenic phase of immunereconstitution, as measured by Ki67 and CD44 expression, and to a renewed thymopoiesis of naive mRNA FoxP3 expressing CD4+CD25+ Tregs after ASCT. Second, using artificial antigen-presenting cells to specifically isolate self-reactive T cells, we demonstrate that ASCT induces autoimmune cells to deviate from a proinflammatory phenotype (mRNA interferon-gamma [IFN-gamma] and T-bet high) to a tolerant phenotype (mRNA interleukin-10 [IL-10] and GATA-3 high). These data are the first to demonstrate the qualitative immunologic changes that are responsible for the induction of immune tolerance by ASCT for JIA: the restoration of the CD4+CD25+ immune regulatory network and reprogramming of autoreactive T cells.

Antigen-Presenting Cells↗
PubMed2005

Fast track selection of immunogens for novel vaccines through visualisation of the early onset of the B-cell response.

A most essential step in vaccine research and development, ie vaccine studies in animals, seriously suffer from long timespans needed to arrive at effective immunogens. In this report we show how almost immediately after vaccination the antibody inducing potential of low immunogenic 'self' antigens can be accurately assessed. (We expect that this timespan can be reduced even more when 'non self' antigens are used, since such responses should be stronger.) The method takes advantage of the immediate onset after vaccination of the immune response in the spleen. This novel method allows detection of antigen-specific B cells of the spleen as early as 7 days after immunization and at frequencies as low as 10 in 1,000,000 cells. The method depends on sequential staining with PE- and APC-conjugated tetramers, made with the same biotinylated peptide. The antigenic peptides are biotinylated and tetramerized with either PE neutravidin or APC streptavidin. We expect that this method can be generally applied to visualize B cell responses, irrespective of the way they are induced. In addition to the fast selection and development of novel immunogens, this procedure can be used to delineate the kinetics of the B cell response, to phenotypically characterize and to isolate antigen-specific B cells, and, perhaps most importantly, to count them at the clonal level before any circulating antibodies can be detected.

Animals↗
PubMed2003

Chromosomal breakpoint mapping by arrayCGH using flow-sorted chromosomes.

Despite the recent completion of the human genome project, the mapping of disease-related chromosomal translocation breakpoints and genes has remained laborious. Here, we describe a novel and rapid procedure to map such translocation breakpoints using flow-sorted chromosomes in combination with array-based comparative genomic hybridization (arrayCGH). To test the feasibility of this approach, we used a t(12;15)(q13;q25)-positive cell line with known breakpoint positions as a model. The derivative 12 chromosomes were flow-sorted, labeled, and hybridized to a genome-wide array containing 3648 well-characterized human genomic clones. The exact locations of the breakpoints on both chromosome 12 and 15 could be determined in a single hybridization experiment. In addition, we have tested the minimal amount of material necessary to perform these experiments and show that it is possible to obtain highly reliable profiles using as little as 10,000 flow-sorted chromosomes.

Chromosome Breakage↗