Friday, September 21, 2007

B Cells Amplify IFN-{gamma} Production By T Cells via a TNF-{alpha}-Mediated Mechanism

J Immunol. 2007 Oct 1;179(7):4857-66

B Cells Amplify IFN-{gamma} Production By T Cells via a TNF-{alpha}-Mediated Mechanism

Menard LC, Minns LA, Darche S, Mielcarz DW, Foureau DM, Roos D, Dzierszinski F, Kasper LH, Buzoni-Gatel D

Departments of Microbiology and Immunology, Dartmouth Medical School, Lebanon, NH 03756.

Aside from being the precursors of the Ab-secreting cells, B cells are engaged in other immune functions such as Ag presentation to T cells or cytokine production. These functions may contribute to the pathogenic role of B cells in a wide range of autoimmune diseases. We demonstrate that B cells acquire the capacity to amplify IFN-gamma production by CD4 and CD8 T cells during the course of the Th1 inflammatory response to Toxoplasma gondii infection. Using the two following different strategies, we observed that B cells from T. gondii-infected mice, but not from naive mice, induce higher IFN-gamma expression by splenic host T cells: 1) reconstitution of B cell-deficient mice with B cells expressing an alloantigen different from the recipients, and 2) adoptive transfer of B and T cells into RAG(-/-) mice. In vitro assays allowing the physical separation of T and B cells demonstrate that Ag-primed B cells enhance IFN-gamma production by T cells in a contact-dependent fashion. Using an OVA-transgenic strain of T. gondii and OVA-specific CD4 T cells, we observed that the proinflammatory effect of B cells is neither Ag specific nor requires MHCII expression. However, TNF-alpha expressed on the surface of B cells appears to mediate in part the up-regulation of IFN-gamma by the effector T cells.

PMID: 17878385 [PubMed - in process]

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