B lymphocytes promote expansion of regulatory T cells in oral tolerance: powerful induction by antigen coupled to cholera toxin B subunit.
Mucosal administration of Ag conjugated to cholera toxin B subunit (CTB) can efficiently induce peripheral immunologic tolerance, so-called oral tolerance, associated with development of Foxp3(+)CD25(+)CD4(+) regulatory T (Treg) cells. Using an established sublingual tolerization regimen with Ag(OVA)/CTB conjugate, wherein CTB mediates Ag uptake and presentation by most B lymphocytes irrespective of their Ag specificity, we have assessed the importance of B cells for induction of Ag-specific Treg cells and oral tolerance. We found that Treg cells are reduced in microMT(-/-) B cell-deficient mice compared with wild-type (WT) mice. After sublingual Ag/CTB treatment, Treg cells increased much more in WT than in microMT(-/-) mice; however, adoptive transfer of B cells before treatment normalized Treg cell development and functional oral tolerance. B cells from OVA/CTB-treated mice expressed more IL-10 and less CD86 than control B cells. Adoptive transfer of these cells before parenteral immunization with OVA led to efficient suppression of proliferation and to induction of apoptotic depletion of Ag-specific CD25(-)CD4(+) effector T cells associated with the expansion of Treg cells. However, also OVA/CTB-treated microMT(-/-) mice could suppress the immune response to parenteral immunization with OVA, which was associated with a strong increase in Foxp3(-)CD4(+) T cells expressing LAP/TGF-beta. Our results indicate that mucosal tolerance comprises at least two separate pathways: one being B cell dependent and associated with expansion of Treg cells and Treg-mediated suppression and depletion of effector T cells, and one being B cell independent and associated with development of Foxp3(-)LAP(+)TGF-beta(+) regulatory T cells.
Sun
Jia-Bin
JB
Department of Microbiology and Immunology, University of Gothenburg Vaccine Research Institute, Institute of Biomedicine Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden. jia-bin.sun@microbio.gu.se
Flach
Carl-Fredrik
CF
Czerkinsky
Cecil
C
Holmgren
Jan
J
D019264:Adoptive Transfer; D000595:Amino Acid Sequence; D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000637:transplantation; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000637:transplantation; D049109:Cell Proliferation; D002772:Cholera Toxin / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000378:metabolism; D005260:Female; D007108:Immune Tolerance; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009061:Mouth Mucosa / Q000166:cytology / Q000276:immunology*; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism; D010446:Peptide Fragments / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism; D021122:Protein Subunits / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology* / Q000637:transplantation
D003432:Cross-Linking Reagents; C111390:OVA 323-339; D010446:Peptide Fragments; D021122:Protein Subunits; D010047:Ovalbumin; D002772:Cholera Toxin