T Regulatory Cells Control Antigen-Induced Recruitment of Mast Cell Progenitors to the Lungs of C57BL/6 Mice

In C57BL/6 mice, the recruitment of mast cell progenitors (MCps) to the lung is a feature of Ag-induced pulmonary inflammation that requires sensitization and challenge and is totally inhibited by the administration of anti-CD4 at the time of challenge. When mAb to TGFbeta1 or to IL-10R was administered at the time of challenge, the recruitment of MCp/10(6) mononuclear cells (MNCs) to the lung was inhibited by 56.3 and 69.6%, respectively, whereas mAb to IL-4, IFN-gamma, IL-6, IL-17A, and IL-17F had no effect. In sensitized and challenged C57BL/6 mice lacking TGFbetaRII on CD4(+) cells, the recruitment of MCp/10(6) MNCs was reduced by 67.8%. The requirement for TGFbeta1 and IL-10 suggested a role for CD4(+)CD25(+) T regulatory cells. Mice treated with anti-CD25 at the time of Ag-challenge showed a reduction in the recruitment of MCp/10(6) MNCs by 77.2% without any reduction in MNC influx. These results reveal an unexpected role for T regulatory cells in promoting the recruitment of MCps to the lungs of C57BL/6 mice with Ag-induced pulmonary inflammation.