NEFL and systemic lupus erythematosus: Increasing levels of NfL were associated with increasing CSF concentrations of anti-P antibodies in pSS patients (B 27.0, 95% CI 10.6–43.3, p = 0.002), but not in SLE (B 11.6, 95% CI – 2.4–25.7, p = 0.10).