Identification of novel autoantibodies to GABAB receptors in patients with neuropsychiatric systemic lupus erythematosus

Methods. ELISA was performed with recombinant proteins of GABAR(B1b) and GABAR(B2) on serum samples from patients with SLE (n = 88), scleroderma (n = 20), myositis (n = 20) or vasculitis (n = 20) as well as healthy subjects (n = 20). Cerebrospinal fluid (CSF) from 23 patients with SLE was also examined. Results. Autoantibodies to GABAR(B)s were exclusive to patients with SLE (P < 0.001) and positively associated with SLEDAI (anti-GABAR(B1b), P = 0.001; anti-GABAR(B2), P < 0.001). Of note, autoantibodies were positively linked with NPSLE (anti-GABAR(B1b), P = 0.02; anti-GABAR(B2), P = 0.03). Moreover, anti-GABAR(B)s was detected in 61.5% of CSF samples from patients with active NPSLE, a frequency that was significantly higher than that for patients with non-SLE syndromes. Conclusion. Anti-GABAR(B) antibodies could represent novel candidate markers for disease activity and NPSLE.