Given that MS-derived exosomes and let-7i could inhibit the in vitro induction of IFNγ−IL-17A−Foxp3+CD4+ Treg cells by acting on naive CD4+ T cells, the observed changes in naive T cells from the peripheral blood of patients with MS suggested that exosomal let-7i may also target naive T cells in vivo. This evidence concerns the gene CD4 and myeloid sarcoma.