1. Polyreactive antigen-binding B cells in the peripheral circulation are IgD+ and B7-.
- Author
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Chen ZJ, Shimizu F, Wheeler J, and Notkins AL
- Subjects
- Antibody-Producing Cells classification, Antigen Presentation, B7-1 Antigen biosynthesis, Cell Adhesion immunology, Cell Line, Flow Cytometry, Humans, Immunophenotyping, Protein Binding immunology, Stem Cells classification, Stem Cells immunology, Up-Regulation immunology, B-Lymphocyte Subsets classification, B-Lymphocyte Subsets immunology, B7-1 Antigen analysis, Immunoglobulin D analysis
- Abstract
Polyreactive antibodies are naturally occurring antibodies, primarily of the IgM isotype, that are capable of reacting with a wide variety of different self and non-self antigens. Previously, we reported that a B cell capable of making polyreactive antibody has Ig receptors on its surface that can bind different antigens. The present investigation was initiated to characterize these polyreactive antigen-binding B cells further. A panel of fluorescein isothiocyanate-labeled antigens (insulin, IgG Fc fragment or beta-galactosidase) served as probes to select polyreactive antigen-binding B cells by cell sorting. Our experiment revealed that these polyreactive antigen-binding B cells were mainly of the IgD isotype. They expressed high levels of CD40 and major histocompatibility complex class II molecules, but little or no B7-1, B7-2, or Fas. In contrast to the binding of antigens to monoreactive receptors (usually high affinity), the binding of antigens to polyreactive receptors (usually moderate or low affinity) did not up-regulate the expression of B7-1 or B7-2. Antigens that bound to polyreactive receptors, however, were internalized and degraded, although not as efficiently as antigens that bound to monoreactive receptors. Despite the ability of these B7- cells to process antigens, they were not able to activate T cells in a mixed leukocyte reaction. It is concluded that polyreactive antigen-binding B cells have properties that are consistent with the ability to induce immunological tolerance.
- Published
- 1996
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