Distinct immune activation patterns in adult-onset Still’s disease with fungal infections

Objective: Fungal infections are uncommon but potentially life-threatening complications in adult-onset Still's disease (AOSD). The immunological features of AOSD patients with fungal infections remain poorly defined, and this study aimed to characterize immune activation profiles in this population. Methods: We retrospectively analyzed 277 patients diagnosed with AOSD, among whom 35 (12.6%) developed fungal infections. Clinical features and immunological parameters, including neutrophil CD64 (nCD64), myeloid-derived suppressor cells (MDSCs), activated T cells, and serum cytokine profiles, were compared between patients with and without fungal infections. Results: T cells (81.54% vs. 66.89%, p < 0.05). Serum soluble IL-2R levels were also higher in infection patients (1884.18 vs. 1259.13 U/mL, p < 0.05). Cytokines such as IL-8, and IL-10 were markedly elevated during infection episodes. Additionally, ferritin elevation remained independently associated with fungal infection after adjusting for disease activity, MAS, and glucocorticoid exposure. Conclusions: T cells, reflecting dynamic immune changes during infection episodes. These immunological features may support integrated immune assessment and inform therapeutic considerations under immunosuppressive treatment.