CD4+CD25+ regulatory T cells generated in response to insulin B:9-23 peptide prevent adoptive transfer of diabetes by diabetogenic T cells.

NOD mice have a relative deficiency of CD4+CD25+ regulatory T cells that could result in an inability to maintain peripheral tolerance. The aim of this study was to induce the generation of CD4+CD25+ regulatory T cells in response to autoantigens to prevent type 1 diabetes (T1D). We found that immunization of NOD mice with insulin B-chain peptide B:9-23 followed by 72 h in vitro culture with B:9-23 peptide induces generation of CD4+CD25+ regulatory T cells. Route of immunization has a critical role in the generation of these cells. Non-autoimmune mice BALB/c, C57BL/6 and NOR did not show up regulation of CD4+CD25+ regulatory T cells. These cells secreted large amounts of TGF-beta and TNF-alpha with little or no IFN-gamma and IL-10. Adoptive transfer of these CD4+CD25+ regulatory T cells into NOD-SCID mice completely prevented the adoptive transfer of disease by diabetogenic T cells. Although, non-self antigenic OVA (323-339) peptide immunization and in vitro culture with OVA (323-339) peptide does result in up regulation of CD4+CD25+ T cells, these cells did not prevent transfer of diabetes. Our study for the first time identified the generation of antigen-specific CD4+CD25+ regulatory T cells specifically in response to immunization with B:9-23 peptide in NOD mice that are capable of blocking adoptive transfer of diabetes. Our results suggest the possibility of using autoantigens to induce antigen-specific regulatory T cells to prevent and regulate autoimmune diabetes.