Long-term stability of autoantibody-based serological profiles in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease marked by diverse autoantibodies. While serological clusters have been associated with distinct clinical phenotypes, most existing studies rely on single time-point assessments and implicitly assume long-term stability of autoantibody profiles. Whether these profiles remain stable over prolonged follow-up has not been systematically evaluated. This study aimed to evaluate the longitudinal serological changes in SLE patients.

A retrospective study was conducted on 82 SLE patients at a hospital in northern Spain. Clinical data and immunological profiles were collected at baseline and during follow-up. Autoantibodies analyzed included ANA, anti-dsDNA, anti-Sm, anti-RNP, anti-SSa (Ro)/SSb (La), and antiphospholipid antibodies (aCL, aB2GPI, LA). Patients were classified into four serological clusters based on baseline antibody profiles.

The cohort was predominantly female (90%), with a mean follow-up of ∼14 years. ANA was positive in nearly all patients. Regarding ANA specificities, anti SSa (Ro) antibodies were the most frequently founded in 28 patients (34%) followed by anti-dsDNA in 19 (23%), anti RNP in 11 (13%), anti SSb (La) in 8 (10%) and lastly anti Sm in 7 (9%). Only 9 of 66 patients (14%) changed serological clusters during follow-up, and most changes did not alter baseline cluster assignment. Most seroconversions involved anti-RNP, anti-Ro, and anti-Sm. Among aPLs, persistent changes occurred in 5 patients, and transient changes in 12. Overall, 86% of patients maintained stable serological profiles.

These findings demonstrate that autoantibody-based serological profiles in SLE are highly stable over long-term follow-up, supporting their validity as enduring disease classifiers with potential prognostic and therapeutic implications.