CD83 and myeloid sarcoma: In contrast, the expression of CD83, CD80, and CD86 on the surface of circulating DCs in patients with PPMS was downregulated, whereas the circulating cDCs of RRMS and SPMS patients showed an activated phenotype, suggesting an imbalance between tolerogenicity and immunogenicity of DCs in MS patients (i.e., functional defects in DCs) (34, 36).