Expansion of a Novel Subset of L-Selectin+ Classical Monocytes in Kawasaki Disease.

Purpose: Kawasaki disease (KD) is an acute systemic vasculitis that is associated with dysregulated immune responses. Monocytes play a central role in innate immunity. Our previous single-cell RNA sequencing of peripheral blood mononuclear cells (PBMC) revealed a new subset of monocytes in children with KD called L-Selectin⁺ classical monocytes (SELL⁺ CM). Therefore, we aimed to investigate the correlation between KD and SELL⁺ CM. Patients and Methods: Peripheral blood samples were collected from 81 KD patients, 18 febrile patients and 36 healthy children before treatment. Among them, ten KD patients were followed up, and samples were obtained before and after intravenous immunoglobulin (IVIG) treatment. Analysis of SELL⁺ CM was performed using flow cytometry. Additionally, ROC curve analysis was conducted to assess the diagnostic value of SELL⁺ CM for KD. Results: Classical monocytes (CM) expressed the highest levels of L-selectin in children with KD. The ratio of SELL⁺ CM in CM was significantly higher in KD patients than in febrile and healthy children. Following IVIG treatment, the ratio of SELL⁺ CM in CM showed a downward trend. The receiver operating characteristic (ROC) curve analysis (the area under the curve, AUC = 0.71) indicated the potential diagnostic value of SELL⁺ CM in KD. The correlation analysis suggested that SELL⁺ CM may serve as a new clinical index for patients with KD. Conclusion: In KD, the ratio of SELL⁺ CM in CM significantly increases during the acute phase, which may become a potential biomarker and help facilitate KD diagnosis based on clinical features. [ABSTRACT FROM AUTHOR]