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Polyreactive antigen-binding B cells in the peripheral circulation are IgD+ and B7-
Z J Chen1, F Shimizu, J Wheeler
1Laboratory of Oral Medicine, National Institute of Dental Research, Bethesda, Maryland 20892-4322, USA.
European Journal of Immunology
|December 1, 1996
Summary
Naturally occurring polyreactive antibodies bind diverse antigens. These B cells, expressing IgD, CD40, and MHC class II, do not activate T cells, suggesting a role in inducing immunological tolerance.
Area of Science:
- Immunology
- B cell biology
Background:
- Polyreactive antibodies, often IgM, bind multiple antigens.
- Previous work identified B cells with polyreactive antigen receptors.
Purpose of the Study:
- Further characterize polyreactive antigen-binding B cells.
- Investigate their surface molecule expression and functional properties.
Main Methods:
- Cell sorting using fluorescein isothiocyanate-labeled antigens (insulin, IgG Fc, beta-galactosidase).
- Analysis of surface marker expression (IgD, CD40, MHC class II, B7-1, B7-2, Fas).
- Antigen uptake, degradation, and T cell activation assays (mixed leukocyte reaction).
Main Results:
- Polyreactive B cells were primarily IgD+ and expressed high CD40 and MHC class II.
- These cells expressed low or no B7-1/B7-2, which were not upregulated by antigen binding.
- Antigen binding led to internalization and degradation, but T cell activation was not observed.
Conclusions:
- Polyreactive B cells exhibit properties consistent with inducing immunological tolerance.
- Their low co-stimulatory molecule expression may prevent T cell activation.