Changes in Treg function are difficult to quantify due to the lack of Treg-exclusive markers in humans and the complexity of functional experiments. We sorted naive and memory human Tregs and conventional T cells, and identified genes that identify human Tregs regardless of their state of activation. We developed this Treg signature using Affymetrix human genome U133A 2.0 microarrays.To generate Tregs and Tconvs in multiple states of activation, naïve (CD4+CD25hiCD45RA+) and memory (CD4+CD25hiCD45RA-) Tregs, and naïve (CD4+CD25-CD45RA+) and memory (CD4+CD25-CD45RA-) Tconvs were sorted from blood of 7 healthy adults and RNA was isolated ex vivo or after stimulation for 40h, promoting activation-induced FOXP3 in Tconvs. The gene-expression profile of the eight cell subsets was analyzed.

7 adult healthy control samples were sorted into 4 subsets: naïve (CD4+CD25hiCD45RA+) and memory (CD4+CD25hiCD45RA-) Tregs, and naïve (CD4+CD25-CD45RA+) and memory (CD4+CD25-CD45RA-) Tconvs. These were used for RNA ex vivo and after 40h stimulation with anti-CD3/CD28 beads to induce an activation phenotype.