Immune Checkpoint Signatures Reveal Stage-Specific Biomarkers for High-Activity Multiple Sclerosis.

The early identification of patients with highly active multiple sclerosis (HAMS) is crucial for guiding therapeutic decisions and initiating high-efficacy treatment strategies. This study aimed to characterize peripheral immune profiles that can distinguish between patients who are candidates for intensive therapy at disease onset and in later stages. Using spectral flow cytometry, we identified distinct immune signatures to differentiate early-stage patients from those with refractory, long-standing disease. In newly diagnosed individuals, decreased herpesvirus entry mediator (HVEM) expression on effector T helper (Th) cells distinguished HAMS from non HAMS cases. In contrast, patients with therapeutic resistance exhibited reduced CD28 expression on naïve regulatory and CD8+ T cells. Disability progression was associated with elevated HVEM on classical monocytes, decreased CD70 on CD56bright natural killer cells (NK), and lower programmed cell death protein 1 (PD-1) expression on memory Th cells. Notably, CD28 expression on terminal effector CD8+ T cells and HVEM levels on plasmablasts emerged as strong predictors of progression independent of relapse activity, while higher PD-1 memory Th cell frequencies predicted clinical stability. This study identifies two panels of immune biomarkers: one distinguishing candidates for early high-efficacy intervention, and another defining patients with refractory disease. The immunological landscape of HAMS evolves across disease stages. In addition, we defined progression-associated markers detectable at the outset of follow-up, enabling the timely recognition of patients at heightened risk of disability accumulation, discriminating between neurodegeneration-driven and inflammation-driven mechanisms of progression.