Increased serum interleukin-39 in patients with myasthenia gravis

Background In 2016, Interleukin-39 (IL-39) was formally acknowledged as a member of the IL-12 cytokine family and identified as a heterodimeric cytokine. It exerts intricate and potentially conflicting functions in the regulation of the immune system, the modulation of inflammatory responses, and the influence on the development of various diseases. Currently, the degree of its participation in myasthenia gravis (MG) still needs to be ascertained. Methods Fifty-one MG patients and 43 healthy controls (HCs) were enrolled. The measurement of serum IL-39 levels was performed with a commercially available ELISA kit. Then, a thorough data analysis was carried out by relating the data to clinical information. Results A significant elevation of serum IL-39 levels was observed in the MG cohort compared to the HC group. Moreover, these levels decreased significantly following immunotherapy. Through ROC curve analysis using IL-39 levels to differentiate MG patients from HCs, the cut-off value was established at 3.41 pg/ml. The analysis showed a specificity of 96.1%, a sensitivity of 86.1%, and an AUC of 0.922 (95% confidence interval: 0.8581–0.9859). Conclusion Significantly elevated serum IL-39 levels are observed in MG patients. Additionally, IL-39 has the potential to be a valuable biomarker for the monitoring of disease activity.