IFNG and primary progressive multiple sclerosis: The IFN-γ/IL-10 ratio was significantly higher in CIS patients than in RRMS patients and HC (p = 0.0156 and p = 0.0491, respectively) and in PPMS patients than in RRMS and SPMS patients and HC (p = 0.0006, p = 0.0185, and p = 0.0083, respectively; Figure 2C).