Transcriptome analysis of Foxp3- CD25- regulatory T cells

The concept of immune regulation/suppression has been well-established. With thymus-derived CD4 CD25 regulatory T (TR) cells, it became clear that a variety of additional peripherally induced TR cells play vital roles in protection from many harmful immune responses including intestinal inflammation. In the present study, we have analyzed in vivo-induced Ag-specific CD4 TR cells with respect to their molecular and functional phenotype. By comparative genomics we could show that these Ag-specific TR cells induced by chronic Ag stimulation in vivo clearly differ in their genetic program from naturally occurring thymus-derived CD4 CD25 TR cells. This distinct population of induced TR cells express neither CD25 nor the TR-associated transcription factor Foxp3. Strikingly, CD25 is not even up-regulated upon stimulation. Despite the lack in Foxp3 expression, these in vivo-induced CD25 TR cells are able to interfere with an Ag-specific CD8 T cell-mediated intestinal inflammation without significant increase in CD25 and Foxp3 expression. Thus, our results demonstrate that in vivo-induced Ag-specific TR cells represent a distinct population of Foxp3 CD25 TR cells with regulatory capacity both in vitro and in vivo. Keywords: cell type comparison To define the molecular signature of Ag-specific in vivo-induced dtg CD25 TR cells in comparison to naturally occurring CD25 TR cells, we performed comparative gene expression profiling by Affymetrix microarray analysis. Sorted splenic wild-type (WT) TR cells, stg TR cells, dtg CD25- TR cells, dtg CD25+ TR cells, in vitro-stimulated stg 16h TA cells, stg 3d TA cells as well as stg TN cells, were included in the experiment and analyses were performed in triplicates.