IL2 and major depressive disorder: The primary outcome was the Piper Fatigue Scale (PFS), and the secondary outcomes were the Insomnia Severity Index (ISI), Hospital Anxiety and Depression Scale (HADS), Interleukin-2 (IL-2), Interleukin-6 (IL-6), CD3+T, and CD4+T. Data analysis was performed using the statistical software SPSS, utilizing descriptive statistics and analytic statistics.