PDCD1 and relapsing-remitting multiple sclerosis: In patients with RRMS, 0.5 mg/kg of fingolimod induces an exhausted-like phenotype, characterized by the inhibition of IL-17 and IFNγ expression, augmentation of IL-10 and TGFβ, and increased expression of exhaustion markers such as programmed cell death-1 (PD-1) and T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) (Dominguez-Villar et al., 2019).