Objective Myasthenia gravis (MG) is an autoimmune disease caused by autoantibodies against neuromuscular junctions. Myasthenic crisis (MC) represents the most severe state of MG with high in‐hospital mortality. We aimed to identify immune signatures using in‐depth profiling in MC, and to assess the correlations between immune biomarkers with clinical severity longitudinally. Methods We studied 181 participants including 57 healthy controls, 96 patients with MG who never experienced crisis and 28 MC patients from December 2018 through June 2020. Follow‐up visits occurred prospectively from crisis to 6 months off‐mechanical ventilation. The frequencies of 20 CD4+ T subpopulations and 18 serum cytokines were associated with clinical scores using correlations and principal component analysis. Results Patients in crisis exhibited a proinflammatory CD4+T response with elevated Th1 (P = 0.026), and Th17 cells (P = 0.032); decreased T follicular helper 2 (Tfh2) cells (P
