It has recently been shown that myelin basic protein (MBP)-hydrolyzing [17–25] and DNase [26–29] activities are intrinsic properties of IgGs, IgMs, and IgAs from sera of MS and SLE patients, autoimmune SLE and experimental autoimmune encephalomyelitis (EAE) mice [30, 31]. This evidence concerns the gene MBP and myeloid sarcoma.