IFNB1 and myeloid sarcoma: In the case of MS, eliminating pathogenic humoral factors from the blood [14], including suspected auto-antibodies directed against the myelin sheath, is needed in some patients with steroid refractory relapses [15], or in patients that develop neutralizing antibodies to interferon-beta (IFN-β), which are associated with reduced bioactivity and efficacy of IFN-β [19,20].