PDCD1 and myeloid sarcoma: In analyzing clusters 0, 2, 6, and 8 in samples from patients with MS versus control (non-MS) samples for expression of these genes, the most notable differences were for cluster 8, which showed, in the patient samples, increases in percentages of expressing cells and/or levels of expression for, among others, BHLHE40, CCL5, ICOS, PDCD1, LTB, PRF1, and MAF, a pattern suggesting cells with enhanced pathogenicity and activation (Supplementary Fig. 4b).