IL17A and myeloid sarcoma: The severe symptoms in the aged patients are more or less attributed to Treg cell function, since Treg cells are regarded as autoimmune protective cells (Buckner, 2010; Furtado et al., 2001; Lowther & Hafler, 2012), which combat IFN‐γ‐producing and IL‐17‐producing CD4+ pathogenic cells and pathogenic CD8+ T cells involved in the MS lesion.