FOXP3 and myeloid sarcoma: Given that expression of the FoxP3 splicing variant containing exon 2 has been associated with immune-suppressive abilities, and that the antibody clone 150D recognizes precisely an epitope encoded by a sequence present in exon 2, we performed a phenotypic study of Treg cells in PBMCs obtained from healthy individuals and MS patients, with the aim of clearly defining the cell subsets expressing FoxP3-E2 within CD4+CD25high cells.