%0 Journal Article %T Characterization of Protective Human CD4+CD25+ FOXP3+ Regulatory T Cells Generated with IL-2, TGF-¦Â and Retinoic Acid %A Ling Lu %A Xiaohui Zhou %A Julie Wang %A Song Guo Zheng %A David A. Horwitz %J PLOS ONE %D 2012 %I Public Library of Science (PLoS) %R 10.1371/journal.pone.0015150 %X Protective CD4+CD25+ regulatory T cells bearing the Forkhead Foxp3 transcription factor can now be divided into three subsets: Endogenous thymus-derived cells, those induced in the periphery, and another subset induced ex-vivo with pharmacological amounts of IL-2 and TGF-¦Â. Unfortunately, endogenous CD4+CD25+ regulatory T cells are unstable and can be converted to effector cells by pro-inflammatory cytokines. Although protective Foxp3+CD4+CD25+ cells resistant to proinflammatory cytokines have been generated in mice, in humans this result has been elusive. Our objective, therefore, was to induce human na£¿ve CD4+ cells to become stable, functional CD25+ Foxp3+ regulatory cells that were also resistant to the inhibitory effects of proinflammatory cytokines. %U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0015150