Tim-3 Upregulation in Monocyte Subsets as a Distinctive Immune Feature and Early Diagnostic Indicator in Systemic Lupus Erythematosus.

INTRODUCTION: Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by immune dysregulation. Tim-3 is an immune checkpoint receptor implicated in various autoimmune conditions. This study aimed to evaluate Tim-3 expression across monocyte subsets in newly diagnosed, treatment-naive SLE patients and assess its clinical relevance and diagnostic potential. METHODS: Peripheral blood samples were analyzed using flow cytometry. Tim-3 expression and its co-expression with HLA-DR/DP/DQ, CD226, and CD62L were assessed. RESULTS: Results showed significantly elevated Tim-3 expression in all monocyte subsets in SLE patients compared to controls. Tim-3+ monocytes exhibited decreased VNN2 level, indicating an activated antigen-presenting phenotype. Upon LPS stimulation, Tim-3+ monocyte subsets secreted more TNF-α. The frequency of Tim-3+ monocytes positively correlated with anti-Ro52 and anti-SSA antibodies, negatively with C3 and IgM levels. ROC curve analysis demonstrated that Tim-3+ monocytes had moderate diagnostic performance for SLE, with area under the curve values of 0.7901. CONCLUSION: These findings suggest that Tim-3+ monocytes may serve as potential biomarkers for early SLE diagnosis.