It has been suggested that they may be attributed to the development of neutralizing antibodies [12], or, as it can be inferred from a recent study [24], to failure of induction of a new regulatory T-cell population, the FoxA1+ regulatory T-cells, that are induced by IFNβ and are found in MS patients that responded to IFNβ therapy. This evidence concerns the gene FOXA1 and myeloid sarcoma.