Description
The relative contribution of induced and natural Foxp3+ regulatory T cells (iTreg and nTreg cells, respectively) to the maintenance of tolerance is unknown. We examined their respective roles by in vivo adoptive transfer immunotherapy of newborn Foxp3-deficient BALB/c mice. Survival, weight gain, tissue infiltration, T cell activation, and the concentration of proinflammatory cytokines were used as outcome measurements. Treatment with iTreg cells alone was not successful. While effective in preventing death, treatment with nTreg cells alone was associated with chronic inflammation and autoimmunity. Outcomes markedly improved when conventional T (Tconv) cells were transferred together with the nTreg cells, where 10% of the peripheral Treg cell pool was derived by in-situ conversion. This enhancement depended upon the capacity of Tconv cells to express Foxp3.