PRF1 and myeloid sarcoma: Freshly isolated peripheral CD8+ T cells from SuS patients expressed the cytotoxic molecules granzyme B (GrB) and perforin (Fig. 3a, Supplementary Fig. 1c) at higher levels than those of healthy individuals and MS patients, in line with increased proportions of CD57+ bona fide CTLs in SuS (Supplementary Fig. 5a).