Human CD4⁺ CD25⁺ CD127^hi cells and the Th1/Th2 phenotype

CD4⁺ T cells that co-express CD25 and CD127 (CD25⁺CD127⁺) make up around 20% of all circulating CD4⁺ memory T cells in healthy people. The clinical significance of these cells is that in children with type 1 diabetes their relative frequency at diagnosis is significantly and directly correlated with rate of disease progression. The purpose of this study was to further characterize the CD25⁺CD127^hi cells. We show that they are a mix of Th1 and Th2 cells however, they have a significantly higher relative frequency of pre-committed and committed Th2 cells, and secrete significantly higher levels of Th2-type cytokines than CD25^- memory T cells. Further, these cells are neither exhausted nor senescent and proliferate to the same extent as CD25^- memory cells. Thus, CD25⁺CD127^hi cells are a highly active subset of memory T cells that might play a role in controlling inflammation via anti-inflammatory Th2-type deviation.