There was no difference in the frequency of IL-17A-producing T cells between HS and nF-MS patients in remission; however, IL-17A-producing T cells increased significantly in nF-MS patients at relapse compared to in remission (the mean frequency, 4.4% vs 0.98%, p = 0.037) (Fig. 5a,b). Here, IL17A is linked to myeloid sarcoma.