Immune Profiling of Refractory cSLE Exposed to CD3×CD19 BiTE

This prospective observational study aims to characterize the peripheral immune landscape of pediatric patients with childhood-onset systemic lupus erythematosus ( cSLE) who are receiving CD3×CD19 bispecific T-cell engager (BiTE) therapy under a separate, approved exploratory clinical study. The present study does not assign, modify, or influence any therapeutic interventions. Peripheral blood samples are collected longitudinally at predefined time points in parallel with routine clinical follow-up. Immune profiling is performed using multiparameter flow cytometry, with single-cell sequencing conducted in a subset of samples to further explore cellular and molecular features. Clinical data, including disease activity indices and relevant serological biomarkers, are recorded concurrently. The objective of this study is to describe immune cell dynamics and immune features associated with changes in disease activity in cSLE, and to explore potential biomarker candidates that may inform future immune-monitoring strategies and mechanistic research in this population.