Relation between T CD4+: Regulatory cells and IL-2 producing cells. Mus musculus

We previously proposed that lymphocyte homeostasis is achieved by a quorum-sensing like mechanism, based on the paracrine sensing of IL-2 by Foxp3(+) regulatory T CD4(+) cells. In turn, these cells will suppress IL-2 producing cells, thereby controlling the total number of T CD4(+) cells. As CD4(+) T regulatory cells are unable to produce IL-2, such control mechanism assumes the complete segregation of both lymphocyte subsets, that is to say they constitute distinct compartments. In the present study, we re-evaluate the above-described quorum-sensing mechanism by considering the non-exclusive possibility that a fraction of IL-2-producing cells might acquire regulatory function, implying the existence of a role for an autocrine sensing of IL-2 in the homeostasis of the regulatory compartment. According to the mouse models used in these experiments, RFP is used as a reporter for the Foxp3 expression. The transcription factor Foxp3 is the main hallmark of T CD4(+) regulatory cells. Therefore RFP(+) cells are associated to T CD4(+) regulatory cells. According to the mouse model, and our last publication (PMID: 24249704), the GFP is a reporter for cells that having activated the IL-2 locus within the last 2-3 weeks. This subset of cells is called IL-2p cells. Overall design: 4 populations of conventional CD4+ T cell are analysed. 5 replicats for each.