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Keywords:

  • Regulatory B cells;
  • colitis, IL-10;
  • enterobacteria

Abstract

Background:

B cells positively contribute to immunity by antigen presentation to CD4+ T cells, cytokine production, and differentiation into antibody secreting plasma cells. Accumulating evidence implies that B cells also possess immunoregulatory functions closely linked to their capability of IL-10 secretion.

Methods:

Colitis development was followed in CD4+CD25 T cell transplanted SCID mice co-transferred with B cells exposed to an enterobacterial extract (ebx-B cells). B and T cell cytokine expression was measured by flow cytometry and enzyme-linked immunosorbent assay (ELISA).

Results:

We demonstrate that splenic B cells exposed to ebx produce large amounts of IL-10 in vitro and express CD1d and CD5 previously known to be associated with regulatory B cells. In SCID mice transplanted with colitogenic CD4+CD25 T cells, co-transfer of ebx-B cells significantly suppressed development of colitis. Suppression was dependent on B cell-derived IL-10, as co-transfer of IL-10 knockout ebx-B cells failed to suppress colitis. Ebx-B cell-mediated suppression of colitis was associated with a decrease in interferon gamma (IFN-γ)-producing TH1 cells and increased frequencies of Foxp3-expressing T cells.

Conclusions:

These data demonstrate that splenic B cells exposed to enterobacterial components acquire immunosuppressive functions by which they can suppress development of experimental T cell-mediated colitis in an IL-10-dependent way. (Inflamm Bowel Dis 2011;)