B-cell subset changes and clinical predictors of telitacicept response in SLE patients with antiphospholipid antibody positivity: a prospective observational cohort study.

Objective: To characterize the dynamic changes in B-cell subsets in Systemic lupus erythematosus (SLE) patients with antiphospholipid antibody (aPL) positivity treated with telitacicept and to identify baseline predictors of treatment response. Methods: Twenty patients with active aPL-positive SLE receiving telitacicept in addition to standard therapy were enrolled, and 20 healthy individuals served as controls. Peripheral blood B-cell subsets and clinical parameters were assessed at baseline, week 12 and week 24. B cell subsets were analyzed using flow cytometry. Multivariable logistic regression was used to identify baseline predictors of SRI-4 response at week 24. Results: At baseline, the proportions of double-negative (DN) B cells and plasmablasts among total B cells were significantly higher in patients with aPL-positive SLE than in healthy controls (both Conclusion: Telitacicept may represent a safe and effective therapeutic option for patients with aPL-positive SLE, potentially exerting its therapeutic effects by influencing B-cell subsets, particularly DN B cells and plasmablasts. Elevated baseline IgG and anti-β2GPI IgG levels may predict a favorable response to telitacicept, and help identify patients who are more likely to benefit from this treatment.